Converta dígitos em palavras com JavaScript

Estou fazendo um código que converte a quantidade dada em palavras, aqui está o que consegui depois de pesquisar no Google. Mas acho que é um código um pouco longo para realizar uma tarefa simples. Duas expressões regulares e dois forloops, quero algo mais simples.

Estou tentando torná-lo o mais curto possível. e vou postar o que eu inventar

Alguma sugestão?

var th = ['','thousand','million', 'billion','trillion'];
var dg = ['zero','one','two','three','four', 'five','six','seven','eight','nine'];
 var tn = ['ten','eleven','twelve','thirteen', 'fourteen','fifteen','sixteen', 'seventeen','eighteen','nineteen'];
 var tw = ['twenty','thirty','forty','fifty', 'sixty','seventy','eighty','ninety'];

function toWords(s) {
    s = s.toString();
    s = s.replace(/[\, ]/g,'');
    if (s != parseFloat(s)) return 'not a number';
    var x = s.indexOf('.');
    if (x == -1)
        x = s.length;
    if (x > 15)
        return 'too big';
    var n = s.split(''); 
    var str = '';
    var sk = 0;
    for (var i=0;   i < x;  i++) {
        if ((x-i)%3==2) { 
            if (n[i] == '1') {
                str += tn[Number(n[i+1])] + ' ';
                i++;
                sk=1;
            } else if (n[i]!=0) {
                str += tw[n[i]-2] + ' ';
                sk=1;
            }
        } else if (n[i]!=0) { // 0235
            str += dg[n[i]] +' ';
            if ((x-i)%3==0) str += 'hundred ';
            sk=1;
        }
        if ((x-i)%3==1) {
            if (sk)
                str += th[(x-i-1)/3] + ' ';
            sk=0;
        }
    }

    if (x != s.length) {
        var y = s.length;
        str += 'point ';
        for (var i=x+1; i<y; i++)
            str += dg[n[i]] +' ';
    }
    return str.replace(/\s+/g,' ');
}

Além disso, o código acima é convertido para o sistema de numeração inglês, como Milhão / Bilhão, não quero um sistema de numeração do Sul da Ásia. como em Lakhs e Crores

Atualização : Parece que isso é mais útil do que eu pensava. Acabei de publicar isso no npm. https://www.npmjs.com/package/num-words

Aqui está um código mais curto. com um RegEx e sem loops. converte como você queria, no sistema de numeração do sul da Ásia

var a = ['','one ','two ','three ','four ', 'five ','six ','seven ','eight ','nine ','ten ','eleven ','twelve ','thirteen ','fourteen ','fifteen ','sixteen ','seventeen ','eighteen ','nineteen '];
var b = ['', '', 'twenty','thirty','forty','fifty', 'sixty','seventy','eighty','ninety'];

function inWords (num) {
    if ((num = num.toString()).length > 9) return 'overflow';
    n = ('000000000' + num).substr(-9).match(/^(\d{2})(\d{2})(\d{2})(\d{1})(\d{2})$/);
    if (!n) return; var str = '';
    str += (n[1] != 0) ? (a[Number(n[1])] || b[n[1][0]] + ' ' + a[n[1][1]]) + 'crore ' : '';
    str += (n[2] != 0) ? (a[Number(n[2])] || b[n[2][0]] + ' ' + a[n[2][1]]) + 'lakh ' : '';
    str += (n[3] != 0) ? (a[Number(n[3])] || b[n[3][0]] + ' ' + a[n[3][1]]) + 'thousand ' : '';
    str += (n[4] != 0) ? (a[Number(n[4])] || b[n[4][0]] + ' ' + a[n[4][1]]) + 'hundred ' : '';
    str += (n[5] != 0) ? ((str != '') ? 'and ' : '') + (a[Number(n[5])] || b[n[5][0]] + ' ' + a[n[5][1]]) + 'only ' : '';
    return str;
}

document.getElementById('number').onkeyup = function () {
    document.getElementById('words').innerHTML = inWords(document.getElementById('number').value);
};

<span id="words"></span>
<input id="number" type="text" />

A única limitação é que você pode converter no máximo 9 dígitos, o que eu acho mais do que suficiente na maioria dos casos.

" Tarefa enganosamente simples." - Potatoswatter

De fato. Existem muitos diabinhos rondando os detalhes desse problema. Foi muito divertido resolver isso.

EDITAR: Esta atualização tem uma abordagem muito mais composicional. Anteriormente, havia uma grande função que envolvia algumas outras funções proprietárias. Em vez disso, desta vez definimos funções reutilizáveis ​​genéricas que podem ser usadas para muitas variedades de tarefas. Mais sobre eles depois de dar uma olhada em numToWordssi ...

// numToWords :: (Number a, String a) => a -> String
let numToWords = n => {
  let a = [
    '', 'one', 'two', 'three', 'four',
    'five', 'six', 'seven', 'eight', 'nine',
    'ten', 'eleven', 'twelve', 'thirteen', 'fourteen',
    'fifteen', 'sixteen', 'seventeen', 'eighteen', 'nineteen'
  ];
  let b = [
    '', '', 'twenty', 'thirty', 'forty',
    'fifty', 'sixty', 'seventy', 'eighty', 'ninety'
  ];
  let g = [
    '', 'thousand', 'million', 'billion', 'trillion', 'quadrillion',
    'quintillion', 'sextillion', 'septillion', 'octillion', 'nonillion'
  ];
  // this part is really nasty still
  // it might edit this again later to show how Monoids could fix this up
  let makeGroup = ([ones,tens,huns]) => {
    return [
      num(huns) === 0 ? '' : a[huns] + ' hundred ',
      num(ones) === 0 ? b[tens] : b[tens] && b[tens] + '-' || '',
      a[tens+ones] || a[ones]
    ].join('');
  };
  // "thousands" constructor; no real good names for this, i guess
  let thousand = (group,i) => group === '' ? group : `${group} ${g[i]}`;
  // execute !
  if (typeof n === 'number') return numToWords(String(n));
  if (n === '0')             return 'zero';
  return comp (chunk(3)) (reverse) (arr(n))
    .map(makeGroup)
    .map(thousand)
    .filter(comp(not)(isEmpty))
    .reverse()
    .join(' ');
};

Aqui estão as dependências:

Você notará que quase nenhuma documentação é necessária porque suas intenções são imediatamente claras. chunkpode ser o único que leva um momento para digerir, mas realmente não é tão ruim. Além disso, o nome da função nos dá uma boa indicação do que ela faz e provavelmente é uma função que encontramos antes.

const arr = x => Array.from(x);
const num = x => Number(x) || 0;
const str = x => String(x);
const isEmpty = xs => xs.length === 0;
const take = n => xs => xs.slice(0,n);
const drop = n => xs => xs.slice(n);
const reverse = xs => xs.slice(0).reverse();
const comp = f => g => x => f (g (x));
const not = x => !x;
const chunk = n => xs =>
  isEmpty(xs) ? [] : [take(n)(xs), ...chunk (n) (drop (n) (xs))];

"Então isso o torna melhor?"

Veja como o código foi limpo significativamente

// NEW CODE (truncated)
return comp (chunk(3)) (reverse) (arr(n))
    .map(makeGroup)
    .map(thousand)
    .filter(comp(not)(isEmpty))
    .reverse()
    .join(' ');

// OLD CODE (truncated)
let grp = n => ('000' + n).substr(-3);
let rem = n => n.substr(0, n.length - 3);
let cons = xs => x => g => x ? [x, g && ' ' + g || '', ' ', xs].join('') : xs;
let iter = str => i => x => r => {
  if (x === '000' && r.length === 0) return str;
  return iter(cons(str)(fmt(x))(g[i]))
             (i+1)
             (grp(r))
             (rem(r));
};
return iter('')(0)(grp(String(n)))(rem(String(n)));

Mais importante ainda, as funções de utilitário que adicionamos no novo código podem ser usadas em outros lugares em seu aplicativo. Isso significa que, como efeito colateral da implementação numToWordsdessa maneira, obtemos as outras funções gratuitamente. Refrigerante bônus!

Alguns testes

console.log(numToWords(11009));
//=> eleven thousand nine

console.log(numToWords(10000001));
//=> ten million one 

console.log(numToWords(987));
//=> nine hundred eighty-seven

console.log(numToWords(1015));
//=> one thousand fifteen

console.log(numToWords(55111222333));
//=> fifty-five billion one hundred eleven million two hundred 
//   twenty-two thousand three hundred thirty-three

console.log(numToWords("999999999999999999999991"));
//=> nine hundred ninety-nine sextillion nine hundred ninety-nine
//   quintillion nine hundred ninety-nine quadrillion nine hundred
//   ninety-nine trillion nine hundred ninety-nine billion nine
//   hundred ninety-nine million nine hundred ninety-nine thousand
//   nine hundred ninety-one

console.log(numToWords(6000753512));
//=> six billion seven hundred fifty-three thousand five hundred
//   twelve 

Demonstração executável

const arr = x => Array.from(x);
const num = x => Number(x) || 0;
const str = x => String(x);
const isEmpty = xs => xs.length === 0;
const take = n => xs => xs.slice(0,n);
const drop = n => xs => xs.slice(n);
const reverse = xs => xs.slice(0).reverse();
const comp = f => g => x => f (g (x));
const not = x => !x;
const chunk = n => xs =>
  isEmpty(xs) ? [] : [take(n)(xs), ...chunk (n) (drop (n) (xs))];

// numToWords :: (Number a, String a) => a -> String
let numToWords = n => {
  
  let a = [
    '', 'one', 'two', 'three', 'four',
    'five', 'six', 'seven', 'eight', 'nine',
    'ten', 'eleven', 'twelve', 'thirteen', 'fourteen',
    'fifteen', 'sixteen', 'seventeen', 'eighteen', 'nineteen'
  ];
  
  let b = [
    '', '', 'twenty', 'thirty', 'forty',
    'fifty', 'sixty', 'seventy', 'eighty', 'ninety'
  ];
  
  let g = [
    '', 'thousand', 'million', 'billion', 'trillion', 'quadrillion',
    'quintillion', 'sextillion', 'septillion', 'octillion', 'nonillion'
  ];
  
  // this part is really nasty still
  // it might edit this again later to show how Monoids could fix this up
  let makeGroup = ([ones,tens,huns]) => {
    return [
      num(huns) === 0 ? '' : a[huns] + ' hundred ',
      num(ones) === 0 ? b[tens] : b[tens] && b[tens] + '-' || '',
      a[tens+ones] || a[ones]
    ].join('');
  };
  
  let thousand = (group,i) => group === '' ? group : `${group} ${g[i]}`;
  
  if (typeof n === 'number')
    return numToWords(String(n));
  else if (n === '0')
    return 'zero';
  else
    return comp (chunk(3)) (reverse) (arr(n))
      .map(makeGroup)
      .map(thousand)
      .filter(comp(not)(isEmpty))
      .reverse()
      .join(' ');
};


console.log(numToWords(11009));
//=> eleven thousand nine

console.log(numToWords(10000001));
//=> ten million one 

console.log(numToWords(987));
//=> nine hundred eighty-seven

console.log(numToWords(1015));
//=> one thousand fifteen

console.log(numToWords(55111222333));
//=> fifty-five billion one hundred eleven million two hundred 
//   twenty-two thousand three hundred thirty-three

console.log(numToWords("999999999999999999999991"));
//=> nine hundred ninety-nine sextillion nine hundred ninety-nine
//   quintillion nine hundred ninety-nine quadrillion nine hundred
//   ninety-nine trillion nine hundred ninety-nine billion nine
//   hundred ninety-nine million nine hundred ninety-nine thousand
//   nine hundred ninety-one

console.log(numToWords(6000753512));
//=> six billion seven hundred fifty-three thousand five hundred
//   twelve

Você pode transpilar o código usando babel.js se quiser ver a variante ES5

Passei um tempo desenvolvendo uma solução melhor para isso. Ele pode lidar com números muito grandes, mas uma vez que eles tenham mais de 16 dígitos, você deve passar o número como uma string. Algo sobre o limite de números de JavaScript.

    function numberToEnglish( n ) {
        
        var string = n.toString(), units, tens, scales, start, end, chunks, chunksLen, chunk, ints, i, word, words, and = 'and';

        /* Remove spaces and commas */
        string = string.replace(/[, ]/g,"");

        /* Is number zero? */
        if( parseInt( string ) === 0 ) {
            return 'zero';
        }
        
        /* Array of units as words */
        units = [ '', 'one', 'two', 'three', 'four', 'five', 'six', 'seven', 'eight', 'nine', 'ten', 'eleven', 'twelve', 'thirteen', 'fourteen', 'fifteen', 'sixteen', 'seventeen', 'eighteen', 'nineteen' ];
        
        /* Array of tens as words */
        tens = [ '', '', 'twenty', 'thirty', 'forty', 'fifty', 'sixty', 'seventy', 'eighty', 'ninety' ];
        
        /* Array of scales as words */
        scales = [ '', 'thousand', 'million', 'billion', 'trillion', 'quadrillion', 'quintillion', 'sextillion', 'septillion', 'octillion', 'nonillion', 'decillion', 'undecillion', 'duodecillion', 'tredecillion', 'quatttuor-decillion', 'quindecillion', 'sexdecillion', 'septen-decillion', 'octodecillion', 'novemdecillion', 'vigintillion', 'centillion' ];
        
        /* Split user argument into 3 digit chunks from right to left */
        start = string.length;
        chunks = [];
        while( start > 0 ) {
            end = start;
            chunks.push( string.slice( ( start = Math.max( 0, start - 3 ) ), end ) );
        }
        
        /* Check if function has enough scale words to be able to stringify the user argument */
        chunksLen = chunks.length;
        if( chunksLen > scales.length ) {
            return '';
        }
        
        /* Stringify each integer in each chunk */
        words = [];
        for( i = 0; i < chunksLen; i++ ) {
            
            chunk = parseInt( chunks[i] );
            
            if( chunk ) {
                
                /* Split chunk into array of individual integers */
                ints = chunks[i].split( '' ).reverse().map( parseFloat );
            
                /* If tens integer is 1, i.e. 10, then add 10 to units integer */
                if( ints[1] === 1 ) {
                    ints[0] += 10;
                }
                
                /* Add scale word if chunk is not zero and array item exists */
                if( ( word = scales[i] ) ) {
                    words.push( word );
                }
                
                /* Add unit word if array item exists */
                if( ( word = units[ ints[0] ] ) ) {
                    words.push( word );
                }
                
                /* Add tens word if array item exists */
                if( ( word = tens[ ints[1] ] ) ) {
                    words.push( word );
                }
                
                /* Add 'and' string after units or tens integer if: */
                if( ints[0] || ints[1] ) {
                    
                    /* Chunk has a hundreds integer or chunk is the first of multiple chunks */
                    if( ints[2] || ! i && chunksLen ) {
                        words.push( and );
                    }
                
                }
                
                /* Add hundreds word if array item exists */
                if( ( word = units[ ints[2] ] ) ) {
                    words.push( word + ' hundred' );
                }
                
            }
            
        }
        
        return words.reverse().join( ' ' );
        
    }


// - - - - - Tests - - - - - -
function test(v) {
  var sep = ('string'==typeof v)?'"':'';
  console.log("numberToEnglish("+sep + v.toString() + sep+") = "+numberToEnglish(v));
}
test(2);
test(721);
test(13463);
test(1000001);
test("21,683,200,000,621,384");

Você pode querer tentar recursivamente. Ele funciona para números entre 0 e 999999. Lembre-se de que (~~) faz o mesmo que Math.floor

var num = "zero one two three four five six seven eight nine ten eleven twelve thirteen fourteen fifteen sixteen seventeen eighteen nineteen".split(" ");
var tens = "twenty thirty forty fifty sixty seventy eighty ninety".split(" ");

function number2words(n){
    if (n < 20) return num[n];
    var digit = n%10;
    if (n < 100) return tens[~~(n/10)-2] + (digit? "-" + num[digit]: "");
    if (n < 1000) return num[~~(n/100)] +" hundred" + (n%100 == 0? "": " " + number2words(n%100));
    return number2words(~~(n/1000)) + " thousand" + (n%1000 != 0? " " + number2words(n%1000): "");
}

Gosto do resultado que obtive aqui, que considero fácil de ler e curto o suficiente para ser uma solução.

function NumInWords (number) {
  const first = ['','one ','two ','three ','four ', 'five ','six ','seven ','eight ','nine ','ten ','eleven ','twelve ','thirteen ','fourteen ','fifteen ','sixteen ','seventeen ','eighteen ','nineteen '];
  const tens = ['', '', 'twenty','thirty','forty','fifty', 'sixty','seventy','eighty','ninety'];
  const mad = ['', 'thousand', 'million', 'billion', 'trillion'];
  let word = '';

  for (let i = 0; i < mad.length; i++) {
    let tempNumber = number%(100*Math.pow(1000,i));
    if (Math.floor(tempNumber/Math.pow(1000,i)) !== 0) {
      if (Math.floor(tempNumber/Math.pow(1000,i)) < 20) {
        word = first[Math.floor(tempNumber/Math.pow(1000,i))] + mad[i] + ' ' + word;
      } else {
        word = tens[Math.floor(tempNumber/(10*Math.pow(1000,i)))] + '-' + first[Math.floor(tempNumber/Math.pow(1000,i))%10] + mad[i] + ' ' + word;
      }
    }

    tempNumber = number%(Math.pow(1000,i+1));
    if (Math.floor(tempNumber/(100*Math.pow(1000,i))) !== 0) word = first[Math.floor(tempNumber/(100*Math.pow(1000,i)))] + 'hunderd ' + word;
  }
    return word;
}

console.log(NumInWords(89754697976431))

E o resultado é:

oitenta e nove trilhões setecentos e cinquenta e quatro bilhões seiscentos e noventa e sete milhões novecentos e setenta e seis mil quatrocentos e trinta e um

Modifiquei o código de MC Shaman para corrigir o bug de um único número ter e aparecer antes dele

function numberToEnglish( n ) {
        
    var string = n.toString(), units, tens, scales, start, end, chunks, chunksLen, chunk, ints, i, word, words, and = 'and';

    /* Remove spaces and commas */
    string = string.replace(/[, ]/g,"");

    /* Is number zero? */
    if( parseInt( string ) === 0 ) {
        return 'zero';
    }
    
    /* Array of units as words */
    units = [ '', 'one', 'two', 'three', 'four', 'five', 'six', 'seven', 'eight', 'nine', 'ten', 'eleven', 'twelve', 'thirteen', 'fourteen', 'fifteen', 'sixteen', 'seventeen', 'eighteen', 'nineteen' ];
    
    /* Array of tens as words */
    tens = [ '', '', 'twenty', 'thirty', 'forty', 'fifty', 'sixty', 'seventy', 'eighty', 'ninety' ];
    
    /* Array of scales as words */
    scales = [ '', 'thousand', 'million', 'billion', 'trillion', 'quadrillion', 'quintillion', 'sextillion', 'septillion', 'octillion', 'nonillion', 'decillion', 'undecillion', 'duodecillion', 'tredecillion', 'quatttuor-decillion', 'quindecillion', 'sexdecillion', 'septen-decillion', 'octodecillion', 'novemdecillion', 'vigintillion', 'centillion' ];
    
    /* Split user argument into 3 digit chunks from right to left */
    start = string.length;
    chunks = [];
    while( start > 0 ) {
        end = start;
        chunks.push( string.slice( ( start = Math.max( 0, start - 3 ) ), end ) );
    }
    
    /* Check if function has enough scale words to be able to stringify the user argument */
    chunksLen = chunks.length;
    if( chunksLen > scales.length ) {
        return '';
    }
    
    /* Stringify each integer in each chunk */
    words = [];
    for( i = 0; i < chunksLen; i++ ) {
        
        chunk = parseInt( chunks[i] );
        
        if( chunk ) {
            
            /* Split chunk into array of individual integers */
            ints = chunks[i].split( '' ).reverse().map( parseFloat );
        
            /* If tens integer is 1, i.e. 10, then add 10 to units integer */
            if( ints[1] === 1 ) {
                ints[0] += 10;
            }
            
            /* Add scale word if chunk is not zero and array item exists */
            if( ( word = scales[i] ) ) {
                words.push( word );
            }
            
            /* Add unit word if array item exists */
            if( ( word = units[ ints[0] ] ) ) {
                words.push( word );
            }
            
            /* Add tens word if array item exists */
            if( ( word = tens[ ints[1] ] ) ) {
                words.push( word );
            }
            
            /* Add 'and' string after units or tens integer if: */
            if( ints[0] || ints[1] ) {
                
                /* Chunk has a hundreds integer or chunk is the first of multiple chunks */
                if( ints[2] || (i + 1) > chunksLen ) {
                    words.push( and );
                }

            
            }
            
            /* Add hundreds word if array item exists */
            if( ( word = units[ ints[2] ] ) ) {
                words.push( word + ' hundred' );
            }
            
        }
        
    }
    
    return words.reverse().join( ' ' );
    
}


// - - - - - Tests - - - - - -

function figure(val) {
  finalFig = numberToEnglish(val);
  document.getElementById("words").innerHTML = finalFig;
}

<span id="words"></span>
<input id="number" type="text" onkeyup=figure(this.value)  />

Converter a string de entrada em um número em vez de mantê-la como uma string limita a solução ao valor máximo de float / inteiro permitido nessa máquina / navegador. Meu script abaixo lida com moedas de até 1 trilhão de dólares - 1 centavo :-). Posso ser estendido para lidar com até 999 trilhões adicionando 3 ou 4 linhas de código.

var ones = ["","One","Two","Three","Four","Five","Six","Seven","Eight",
            "Nine","Ten","Eleven","Twelve","Thirteen","Fourteen",
            "Fifteen","Sixteen","Seventeen","Eighteen","Nineteen"]; 

var tens = ["","","Twenty","Thirty","Forty","Fifty","Sixty","Seventy",
            "Eighty","Ninety"]; 


function words999(n999)   {    // n999 is an integer less than or equal to 999.
//
// Accept any 3 digit int incl 000 & 999 and return words.
// 

    var words = ''; var Hn = 0; var n99 = 0;

    Hn = Math.floor(n999 / 100);                  // # of hundreds in it

    if (Hn > 0)   {                               // if at least one 100

      words = words99(Hn) + " Hundred";           // one call for hundreds
    }

    n99 = n999 - (Hn * 100);                      // subtract the hundreds.

    words += ((words == '')?'':' ') + words99(n99); // combine the hundreds with tens & ones.

    return words;
}                            // function words999( n999 )

function words99(n99)   {    // n99 is an integer less than or equal to 99.
//
// Accept any 2 digit int incl 00 & 99 and return words.
// 

    var words = ''; var Dn = 0; var Un = 0;

    Dn = Math.floor(n99 / 10);           // # of tens

    Un = n99 % 10;                       // units

    if (Dn > 0 || Un > 0) {

      if (Dn < 2) {

        words += ones[Dn * 10 + Un];     // words for a # < 20

      } else {

        words += tens[Dn];

        if (Un > 0) words += "-" + ones[Un];
      }
    }                               // if ( Dn > 0 || Un > 0 )

    return words;
}                                   // function words99( n99 )

function getAmtInWords(id1, id2) {  // use numeric value of id1 to populate text in id2 
//
// Read numeric amount field and convert into word amount
// 

    var t1 = document.getElementById(id1).value;

    var t2 = t1.trim();

    amtStr = t2.replace(/,/g,'');        // $123,456,789.12 = 123456789.12

    dotPos = amtStr.indexOf('.');        // position of dot before cents, -ve if it doesn't exist.

    if (dotPos > 0) {

      dollars = amtStr.slice(0,dotPos);  // 1234.56 = 1234
      cents   = amtStr.slice(dotPos+1);  // 1234.56 = .56

    } else if (dotPos == 0) {

      dollars = '0';
      cents   = amtStr.slice(dotPos+1);  // 1234.56 = .56

    } else {

      dollars = amtStr.slice(0);         // 1234 = 1234
      cents   = '0'; 
    }

    t1      = '000000000000' + dollars;  // to extend to trillion, use 15 zeros
    dollars =  t1.slice(-12);            // and -15 here.

    billions  = Number(dollars.substr(0,3));
    millions  = Number(dollars.substr(3,3));
    thousands = Number(dollars.substr(6,3));
    hundreds  = Number(dollars.substr(9,3));

    t1 = words999(billions);    bW = t1.trim();   // Billions  in words

    t1 = words999(millions);    mW = t1.trim();   // Millions  in words

    t1 = words999(thousands);   tW = t1.trim();   // Thousands in words

    t1 = words999(hundreds);    hW = t1.trim();   // Hundreds  in words

    t1 = words99(cents);        cW = t1.trim();   // Cents     in words

    var totAmt = '';

    if (bW != '')   totAmt += ((totAmt != '') ? ' '  : '') + bW + ' Billion';
    if (mW != '')   totAmt += ((totAmt != '') ? ' '  : '') + mW + ' Million';
    if (tW != '')   totAmt += ((totAmt != '') ? ' '  : '') + tW + ' Thousand';
    if (hW != '')   totAmt += ((totAmt != '') ? ' '  : '') + hW + ' Dollars';

    if (cW != '')   totAmt += ((totAmt != '') ? ' and ' : '') + cW + ' Cents';

//  alert('totAmt = ' + totAmt);    // display words in a alert

    t1 = document.getElementById(id2).value;

    t2 = t1.trim();

    if (t2 == '')  document.getElementById(id2).value = totAmt;

    return false;
}                        // function getAmtInWords( id1, id2 )

// ======================== [ End Code ] ====================================

Se você precisar com o Cent, então você pode usar este

        <script>
            var iWords = ['zero', ' one', ' two', ' three', ' four', ' five', ' six', ' seven', ' eight', ' nine'];
            var ePlace = ['ten', ' eleven', ' twelve', ' thirteen', ' fourteen', ' fifteen', ' sixteen', ' seventeen', ' eighteen', ' nineteen'];
            var tensPlace = ['', ' ten', ' twenty', ' thirty', ' forty', ' fifty', ' sixty', ' seventy', ' eighty', ' ninety'];
            var inWords = [];

            var numReversed, inWords, actnumber, i, j;

            function tensComplication() {
            if (actnumber[i] == 0) {
                inWords[j] = '';
            } else if (actnumber[i] == 1) {
                inWords[j] = ePlace[actnumber[i - 1]];
            } else {
                inWords[j] = tensPlace[actnumber[i]];
            }
            }

            function convertAmount() {
                var numericValue = document.getElementById('bdt').value;
                numericValue = parseFloat(numericValue).toFixed(2);

                var amount = numericValue.toString().split('.');
                var taka = amount[0];
                var paisa = amount[1];
                document.getElementById('container').innerHTML = convert(taka) +" taka and "+ convert(paisa)+" paisa only";
            }
            function convert(numericValue) {
            inWords = []
            if(numericValue == "00" || numericValue =="0"){
                return 'zero';
            }
            var obStr = numericValue.toString();
            numReversed = obStr.split('');
            actnumber = numReversed.reverse();


            if (Number(numericValue) == 0) {
                document.getElementById('container').innerHTML = 'BDT Zero';
                return false;
            }

            var iWordsLength = numReversed.length;
            var finalWord = '';
            j = 0;
            for (i = 0; i < iWordsLength; i++) {
                switch (i) {
                    case 0:
                        if (actnumber[i] == '0' || actnumber[i + 1] == '1') {
                            inWords[j] = '';
                        } else {
                            inWords[j] = iWords[actnumber[i]];
                        }
                        inWords[j] = inWords[j] + '';
                        break;
                    case 1:
                        tensComplication();
                        break;
                    case 2:
                        if (actnumber[i] == '0') {
                            inWords[j] = '';
                        } else if (actnumber[i - 1] !== '0' && actnumber[i - 2] !== '0') {
                            inWords[j] = iWords[actnumber[i]] + ' hundred';
                        } else {
                            inWords[j] = iWords[actnumber[i]] + ' hundred';
                        }
                        break;
                    case 3:
                        if (actnumber[i] == '0' || actnumber[i + 1] == '1') {
                            inWords[j] = '';
                        } else {
                            inWords[j] = iWords[actnumber[i]];
                        }
                        if (actnumber[i + 1] !== '0' || actnumber[i] > '0') {
                            inWords[j] = inWords[j] + ' thousand';
                        }
                        break;
                    case 4:
                        tensComplication();
                        break;
                    case 5:
                        if (actnumber[i] == '0' || actnumber[i + 1] == '1') {
                            inWords[j] = '';
                        } else {
                            inWords[j] = iWords[actnumber[i]];
                        }
                        if (actnumber[i + 1] !== '0' || actnumber[i] > '0') {
                            inWords[j] = inWords[j] + ' lakh';
                        }
                        break;
                    case 6:
                        tensComplication();
                        break;
                    case 7:
                        if (actnumber[i] == '0' || actnumber[i + 1] == '1') {
                            inWords[j] = '';
                        } else {
                            inWords[j] = iWords[actnumber[i]];
                        }
                        inWords[j] = inWords[j] + ' crore';
                        break;
                    case 8:
                        tensComplication();
                        break;
                    default:
                        break;
                }
                j++;
            }


            inWords.reverse();
            for (i = 0; i < inWords.length; i++) {
                finalWord += inWords[i];
            }
            return finalWord;
            }

        </script>

        <input type="text" name="bdt" id="bdt" />
        <input type="button" name="sr1" value="Click Here" onClick="convertAmount()"/>

        <div id="container"></div>

js violino

Aqui taka significa USD e paisa significa cent.

Esta é uma resposta ao comentário de @LordZardeck à excelente resposta de @naomik acima . Desculpe, eu teria comentado diretamente, mas nunca postei antes, então não tenho o privilégio de fazer isso, então estou postando aqui.

De qualquer forma, acabei de traduzir a versão ES5 para um formato mais legível no fim de semana passado, então estou compartilhando aqui. Deve ser fiel ao original (incluindo a edição recente) e espero que a nomenclatura seja clara e precisa.

function int_to_words(int) {
  if (int === 0) return 'zero';

  var ONES  = ['','one','two','three','four','five','six','seven','eight','nine','ten','eleven','twelve','thirteen','fourteen','fifteen','sixteen','seventeen','eighteen','nineteen'];
  var TENS  = ['','','twenty','thirty','fourty','fifty','sixty','seventy','eighty','ninety'];
  var SCALE = ['','thousand','million','billion','trillion','quadrillion','quintillion','sextillion','septillion','octillion','nonillion'];

  // Return string of first three digits, padded with zeros if needed
  function get_first(str) {
    return ('000' + str).substr(-3);
  }

  // Return string of digits with first three digits chopped off
  function get_rest(str) {
    return str.substr(0, str.length - 3);
  }

  // Return string of triplet convereted to words
  function triplet_to_words(_3rd, _2nd, _1st) {
    return (_3rd == '0' ? '' : ONES[_3rd] + ' hundred ') + (_1st == '0' ? TENS[_2nd] : TENS[_2nd] && TENS[_2nd] + '-' || '') + (ONES[_2nd + _1st] || ONES[_1st]);
  }

  // Add to words, triplet words with scale word
  function add_to_words(words, triplet_words, scale_word) {
    return triplet_words ? triplet_words + (scale_word && ' ' + scale_word || '') + ' ' + words : words;
  }

  function iter(words, i, first, rest) {
    if (first == '000' && rest.length === 0) return words;
    return iter(add_to_words(words, triplet_to_words(first[0], first[1], first[2]), SCALE[i]), ++i, get_first(rest), get_rest(rest));
  }

  return iter('', 0, get_first(String(int)), get_rest(String(int)));
}

var inWords = function(totalRent){
//console.log(totalRent);
var a = ['','one ','two ','three ','four ', 'five ','six ','seven ','eight ','nine ','ten ','eleven ','twelve ','thirteen ','fourteen ','fifteen ','sixteen ','seventeen ','eighteen ','nineteen '];
var b = ['', '', 'twenty','thirty','forty','fifty', 'sixty','seventy','eighty','ninety'];
var number = parseFloat(totalRent).toFixed(2).split(".");
var num = parseInt(number[0]);
var digit = parseInt(number[1]);
//console.log(num);
if ((num.toString()).length > 9)  return 'overflow';
var n = ('000000000' + num).substr(-9).match(/^(\d{2})(\d{2})(\d{2})(\d{1})(\d{2})$/);
var d = ('00' + digit).substr(-2).match(/^(\d{2})$/);;
if (!n) return; var str = '';
str += (n[1] != 0) ? (a[Number(n[1])] || b[n[1][0]] + ' ' + a[n[1][1]]) + 'crore ' : '';
str += (n[2] != 0) ? (a[Number(n[2])] || b[n[2][0]] + ' ' + a[n[2][1]]) + 'lakh ' : '';
str += (n[3] != 0) ? (a[Number(n[3])] || b[n[3][0]] + ' ' + a[n[3][1]]) + 'thousand ' : '';
str += (n[4] != 0) ? (a[Number(n[4])] || b[n[4][0]] + ' ' + a[n[4][1]]) + 'hundred ' : '';
str += (n[5] != 0) ? (a[Number(n[5])] || b[n[5][0]] + ' ' + a[n[5][1]]) + 'Rupee ' : '';
str += (d[1] != 0) ? ((str != '' ) ? "and " : '') + (a[Number(d[1])] || b[d[1][0]] + ' ' + a[d[1][1]]) + 'Paise ' : 'Only!';
console.log(str);
return str;
}

Este é um código modificado que suporta a Rúpia Indiana com 2 casas decimais.

Outra conversão que usa restos e oferece suporte a diferentes idiomas:

function numberToWords(number) {
  var result = [];

  var fraction = number.toFixed(2).split('.');
  var integer_part = parseInt(fraction[0]);
  // var fractional_part = parseInt(fraction[1]); -- not handled here

  var previousNumber = null;
  for (var i = 0; i < fraction[0].length; i++) {
    var reminder = Math.floor(integer_part % 10);
    integer_part /= 10;
    var name = getNumberName(reminder, i, fraction[0].length, previousNumber);
    previousNumber = reminder;
    if (name)
      result.push(name);
  }

  result.reverse();
  return result.join(' ');
}

A getNumberNamefunção depende do idioma e controla números até 9999 (mas é fácil estendê-la para lidar com números maiores):

function getNumberName(number, power, places, previousNumber) {
  var result = "";
  if (power == 1) {
    result = handleTeensAndTys(number, previousNumber);
  } else if (power == 0 && places != 1 || number == 0) {
    // skip number that was handled in teens and zero
  } else {
    result = locale.numberNames[number.toString()] + locale.powerNames[power.toString()];
  }

  return result;
}

handleTeensAndTys lida com múltiplos de dez:

function handleTeensAndTys(number, previousNumber) {
  var result = "";
  if (number == 1) { // teens
    if (previousNumber in locale.specialTeenNames) {
      result = locale.specialTeenNames[previousNumber];    
    } else if (previousNumber in locale.specialTyNames) {
      result = locale.specialTyNames[previousNumber] + locale.teenSuffix;
    } else {
      result = locale.numberNames[previousNumber] + locale.teenSuffix;    
    }
  } else if (number == 0) { // previousNumber was not handled in teens
    result = locale.numberNames[previousNumber.toString()];
  } else { // other tys
    if (number in locale.specialTyNames) {
      result = locale.specialTyNames[number];
    } else {
      result = locale.numberNames[number];
    }
    result += locale.powerNames[1];
    if (previousNumber != 0) {
      result += " " + locale.numberNames[previousNumber.toString()];
    }
  }
  return result;
}

Finalmente, exemplos de localidade:

var locale = { // English
  numberNames: {1: "one", 2: "two", 3: "three", 4: "four", 5: "five", 6: "six", 7: "seven", 8: "eight", 9: "nine" },
  powerNames: {0: "", 1: "ty", 2: " hundred", 3: " thousand" },
  specialTeenNames: {0: "ten", 1: "eleven", 2: "twelve" },
  specialTyNames: {2: "twen", 3: "thir", 5: "fif" },
  teenSuffix: "teen"
};

var locale = { // Estonian
  numberNames: {1: "üks", 2: "kaks", 3: "kolm", 4: "neli", 5: "viis", 6: "kuus", 7: "seitse", 8: "kaheksa", 9: "üheksa"},
  powerNames: {0: "", 1: "kümmend", 2: "sada", 3: " tuhat" },
  specialTeenNames: {0: "kümme"},
  specialTyNames: {},
  teenSuffix: "teist"
};

Aqui está um JSFiddle com testes: https://jsfiddle.net/rcrxna7v/15/

Modifiquei o código de @McShaman, converti-o em CoffeeScript e adicionei documentos via JSNice . Aqui está o resultado, para os interessados ​​(inglês):

###
    Convert an integer to an English string equivalent
    @param {Integer} number the integer to be converted
    @return {String} the English number equivalent
###
inWords = (number) ->
    ###
        @property {Array}
    ###
    englishIntegers = [
        ""
        "one "
        "two "
        "three "
        "four "
        "five "
        "six "
        "seven "
        "eight "
        "nine "
        "ten "
        "eleven "
        "twelve "
        "thirteen "
        "fourteen "
        "fifteen "
        "sixteen "
        "seventeen "
        "eighteen "
        "nineteen "
    ]

    ###
        @property {Array}
    ###
    englishIntegerTens = [
        ""
        ""
        "twenty"
        "thirty"
        "forty"
        "fifty"
        "sixty"
        "seventy"
        "eighty"
        "ninety"
    ]

    ###
        @property {Array}
    ###
    englishIntegerThousands = [
        "thousand"
        "million"
        ""
    ]
    number = number.toString()
    return "" if number.length > 9

    ###
        @property {string}
    ###
    number = ("000000000" + number).substr(-9)

    ###
      @property {(Array.<string>|null)}
      ###
    number = number.match(/.{3}/g)

    ###
        @property {string}
    ###
    convertedWords = ""

    ###
        @property {number}
    ###
    i = 0
    while i < englishIntegerThousands.length

        ###
            @property {string}
        ###
        currentNumber = number[i]

        ###
            @property {string}
        ###
        tempResult = ""
        tempResult += (if convertedWords isnt "" then " " + englishIntegerThousands[i] + " " else "")
        tempResult += (if currentNumber[0] isnt 0 then englishIntegers[Number(currentNumber[0])] + "hundred " else "")

        ###
            @property {string}
        ###
        currentNumber = currentNumber.substr(1)
        tempResult += (if currentNumber isnt 0 then ((if tempResult isnt "" then "and " else "")) + (englishIntegers[Number(currentNumber)] or englishIntegerTens[currentNumber[0]] + " " + englishIntegers[currentNumber[1]]) else "")
        convertedWords += tempResult
        i++
    convertedWords

Porém, esta pergunta foi respondida - ainda quero compartilhar algo que desenvolvi recentemente em java script (com base na lógica de uma implementação C # .Net antiga que encontrei na Internet) para converter valores de moeda indiana em palavras. Ele pode lidar com até 40 dígitos. Você pode dar uma olhada.

Uso: InrToWordConverter.Initialize () ;. var inWords = InrToWordConverter.ConvertToWord (montante);

Implementação:

htPunctuation = {};
listStaticSuffix = {};
listStaticPrefix = {};
listHelpNotation = {};

var InrToWordConverter = function () {

};

InrToWordConverter.Initialize = function () {
    InrToWordConverter.LoadStaticPrefix();
    InrToWordConverter.LoadStaticSuffix();
    InrToWordConverter.LoadHelpofNotation();
};

InrToWordConverter.ConvertToWord = function (value) {
    value = value.toString();

    if (value) {
        var tokens = value.split(".");
        var rsPart = "";
        var psPart = "";
        if (tokens.length === 2) {
            rsPart = String.trim(tokens[0]) || "0";
            psPart = String.trim(tokens[1]) || "0";
        }
        else if (tokens.length === 1) {
            rsPart = String.trim(tokens[0]) || "0";
            psPart = "0";
        }
        else {
            rsPart = "0";
            psPart = "0";
        }

        htPunctuation = {};
        var rsInWords = InrToWordConverter.ConvertToWordInternal(rsPart) || "Zero";
        var psInWords = InrToWordConverter.ConvertToWordInternal(psPart) || "Zero";

        var result = "Rupees " + rsInWords + "and " + psInWords + " Paise.";
        return result;
    }
};

InrToWordConverter.ConvertToWordInternal = function (value) {
    var convertedString = "";
    if (!(value.toString().length > 40))
    {
        if (InrToWordConverter.IsNumeric(value.toString()))
        {
            try
            {
                var strValue = InrToWordConverter.Reverse(value);
                switch (strValue.length)
                {
                    case 1:
                        if (parseInt(strValue.toString()) > 0) {
                            convertedString = InrToWordConverter.GetWordConversion(value);
                        }
                        else {
                            convertedString = "Zero ";
                        }
                        break;
                    case 2:
                        convertedString = InrToWordConverter.GetWordConversion(value);
                        break;
                    default:
                        InrToWordConverter.InsertToPunctuationTable(strValue);
                        InrToWordConverter.ReverseHashTable();
                        convertedString = InrToWordConverter.ReturnHashtableValue();
                        break;
                }
            }
            catch (exception) {
                convertedString = "Unexpected Error Occured <br/>";
            }
        }
        else {
            convertedString = "Please Enter Numbers Only, Decimal Values Are not supported";
        }
    }
    else {
        convertedString = "Please Enter Value in Less Then or Equal to 40 Digit";
    }
    return convertedString;
};

InrToWordConverter.IsNumeric = function (valueInNumeric) {
    var isFine = true;
    valueInNumeric = valueInNumeric || "";
    var len = valueInNumeric.length;
    for (var i = 0; i < len; i++) {
        var ch = valueInNumeric[i];
        if (!(ch >= '0' && ch <= '9')) {
            isFine = false;
            break;
        }
    }
    return isFine;
};

InrToWordConverter.ReturnHashtableValue = function () {
    var strFinalString = "";
    var keysArr = [];
    for (var key in htPunctuation) {
        keysArr.push(key);
    }
    for (var i = keysArr.length - 1; i >= 0; i--) {
        var hKey = keysArr[i];
        if (InrToWordConverter.GetWordConversion((htPunctuation[hKey]).toString()) !== "") {
            strFinalString = strFinalString + InrToWordConverter.GetWordConversion((htPunctuation[hKey]).toString()) + InrToWordConverter.StaticPrefixFind((hKey).toString());
        }
    }
    return strFinalString;
};

InrToWordConverter.ReverseHashTable = function () {
    var htTemp = {};
    for (var key in htPunctuation) {
        var item = htPunctuation[key];
        htTemp[key] = InrToWordConverter.Reverse(item.toString());
    }
    htPunctuation = {};
    htPunctuation = htTemp;
};

InrToWordConverter.InsertToPunctuationTable = function (strValue) {
    htPunctuation[1] = strValue.substr(0, 3).toString();
    var j = 2;
    for (var i = 3; i < strValue.length; i = i + 2) {
        if (strValue.substr(i).length > 0) {
            if (strValue.substr(i).length >= 2) {
                htPunctuation[j] = strValue.substr(i, 2).toString();
            }
            else {
                htPunctuation[j] = strValue.substr(i, 1).toString();
            }
        }
        else {
            break;
        }
        j++;

    }
};

InrToWordConverter.Reverse = function (strValue) {
    var reversed = "";
    for (var i in strValue) {
        var ch = strValue[i];
        reversed = ch + reversed;
    }
    return reversed;
};

InrToWordConverter.GetWordConversion = function (inputNumber) {
    var toReturnWord = "";
    if (inputNumber.length <= 3 && inputNumber.length > 0) {
        if (inputNumber.length === 3) {
            if (parseInt(inputNumber.substr(0, 1)) > 0) {
                toReturnWord = toReturnWord + InrToWordConverter.StaticSuffixFind(inputNumber.substr(0, 1)) + "Hundred ";
            }

            var tempString = InrToWordConverter.StaticSuffixFind(inputNumber.substr(1, 2));

            if (tempString === "")
            {
                toReturnWord = toReturnWord + InrToWordConverter.StaticSuffixFind(inputNumber.substr(1, 1) + "0");
                toReturnWord = toReturnWord + InrToWordConverter.StaticSuffixFind(inputNumber.substr(2, 1));
            }
            toReturnWord = toReturnWord + tempString;
        }
        if (inputNumber.length === 2)
        {
            var tempString = InrToWordConverter.StaticSuffixFind(inputNumber.substr(0, 2));
            if (tempString === "")
            {
                toReturnWord = toReturnWord + InrToWordConverter.StaticSuffixFind(inputNumber.substr(0, 1) + "0");
                toReturnWord = toReturnWord + InrToWordConverter.StaticSuffixFind(inputNumber.substr(1, 1));
            }
            toReturnWord = toReturnWord + tempString;
        }
        if (inputNumber.length === 1)
        {
            toReturnWord = toReturnWord + InrToWordConverter.StaticSuffixFind(inputNumber.substr(0, 1));
        }

    }
    return toReturnWord;
};

InrToWordConverter.StaticSuffixFind = function (numberKey) {
    var valueFromNumber = "";
    for (var key in listStaticSuffix) {
        if (String.trim(key.toString()) === String.trim(numberKey)) {
            valueFromNumber = listStaticSuffix[key].toString();
            break;
        }
    }
    return valueFromNumber;
};

InrToWordConverter.StaticPrefixFind = function (numberKey) {
    var valueFromNumber = "";
    for (var key in listStaticPrefix) {
        if (String.trim(key) === String.trim(numberKey)) {
            valueFromNumber = listStaticPrefix[key].toString();
            break;
        }
    }
    return valueFromNumber;
};

InrToWordConverter.StaticHelpNotationFind = function (numberKey) {
    var helpText = "";
    for (var key in listHelpNotation) {
        if (String.trim(key.toString()) === String.trim(numberKey)) {
            helpText = listHelpNotation[key].toString();
            break;
        }
    }
    return helpText;
};

InrToWordConverter.LoadStaticPrefix = function () {
    listStaticPrefix[2] = "Thousand ";
    listStaticPrefix[3] = "Lac ";
    listStaticPrefix[4] = "Crore ";
    listStaticPrefix[5] = "Arab ";
    listStaticPrefix[6] = "Kharab ";
    listStaticPrefix[7] = "Neel ";
    listStaticPrefix[8] = "Padma ";
    listStaticPrefix[9] = "Shankh ";
    listStaticPrefix[10] = "Maha-shankh ";
    listStaticPrefix[11] = "Ank ";
    listStaticPrefix[12] = "Jald ";
    listStaticPrefix[13] = "Madh ";
    listStaticPrefix[14] = "Paraardha ";
    listStaticPrefix[15] = "Ant ";
    listStaticPrefix[16] = "Maha-ant ";
    listStaticPrefix[17] = "Shisht ";
    listStaticPrefix[18] = "Singhar ";
    listStaticPrefix[19] = "Maha-singhar ";
    listStaticPrefix[20] = "Adant-singhar ";
};

InrToWordConverter.LoadStaticSuffix = function () {
    listStaticSuffix[1] = "One ";
    listStaticSuffix[2] = "Two ";
    listStaticSuffix[3] = "Three ";
    listStaticSuffix[4] = "Four ";
    listStaticSuffix[5] = "Five ";
    listStaticSuffix[6] = "Six ";
    listStaticSuffix[7] = "Seven ";
    listStaticSuffix[8] = "Eight ";
    listStaticSuffix[9] = "Nine ";
    listStaticSuffix[10] = "Ten ";
    listStaticSuffix[11] = "Eleven ";
    listStaticSuffix[12] = "Twelve ";
    listStaticSuffix[13] = "Thirteen ";
    listStaticSuffix[14] = "Fourteen ";
    listStaticSuffix[15] = "Fifteen ";
    listStaticSuffix[16] = "Sixteen ";
    listStaticSuffix[17] = "Seventeen ";
    listStaticSuffix[18] = "Eighteen ";
    listStaticSuffix[19] = "Nineteen ";
    listStaticSuffix[20] = "Twenty ";
    listStaticSuffix[30] = "Thirty ";
    listStaticSuffix[40] = "Fourty ";
    listStaticSuffix[50] = "Fifty ";
    listStaticSuffix[60] = "Sixty ";
    listStaticSuffix[70] = "Seventy ";
    listStaticSuffix[80] = "Eighty ";
    listStaticSuffix[90] = "Ninty ";
};

InrToWordConverter.LoadHelpofNotation = function () {
    listHelpNotation[2] = "=1,000 (3 Trailing Zeros)";
    listHelpNotation[3] = "=1,00,000 (5 Trailing Zeros)";
    listHelpNotation[4] = "=1,00,00,000 (7 Trailing Zeros)";
    listHelpNotation[5] = "=1,00,00,00,000 (9 Trailing Zeros)";
    listHelpNotation[6] = "=1,00,00,00,00,000 (11 Trailing Zeros)";
    listHelpNotation[7] = "=1,00,00,00,00,00,000 (13 Trailing Zeros)";
    listHelpNotation[8] = "=1,00,00,00,00,00,00,000 (15 Trailing Zeros)";
    listHelpNotation[9] = "=1,00,00,00,00,00,00,00,000 (17 Trailing Zeros)";
    listHelpNotation[10] = "=1,00,00,00,00,00,00,00,00,000 (19 Trailing Zeros)";
    listHelpNotation[11] = "=1,00,00,00,00,00,00,00,00,00,000 (21 Trailing Zeros)";
    listHelpNotation[12] = "=1,00,00,00,00,00,00,00,00,00,00,000 (23 Trailing Zeros)";
    listHelpNotation[13] = "=1,00,00,00,00,00,00,00,00,00,00,00,000 (25 Trailing Zeros)";
    listHelpNotation[14] = "=1,00,00,00,00,00,00,00,00,00,00,00,00,000 (27 Trailing Zeros)";
    listHelpNotation[15] = "=1,00,00,00,00,00,00,00,00,00,00,00,00,00,000 (29 Trailing Zeros)";
    listHelpNotation[16] = "=1,00,00,00,00,00,00,00,00,00,00,00,00,00,00,000 (31 Trailing Zeros)";
    listHelpNotation[17] = "=1,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,000 (33 Trailing Zeros)";
    listHelpNotation[18] = "=1,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,000 (35 Trailing Zeros)";
    listHelpNotation[19] = "=1,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,000 (37 Trailing Zeros)";
    listHelpNotation[20] = "=1,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,000 (39 Trailing Zeros)";
};
    if (!String.trim) {
    String.trim = function (str) {
        var result = "";
        var firstNonWhiteSpaceFound = false;
        var startIndex = -1;
        var endIndex = -1;
        if (str) {
            for (var i = 0; i < str.length; i++) {
                if (firstNonWhiteSpaceFound === false) {
                    if (str[i] === ' ' || str[i] === '\t') {
                        continue;
                    }
                    else {
                        firstNonWhiteSpaceFound = true;
                        startIndex = i;
                        endIndex = i;
                    }
                }
                else {
                    if (str[i] === ' ' || str[i] === '\t') {
                        continue;
                    }
                    else {
                        endIndex = i;
                    }
                }
            }
            if (startIndex !== -1 && endIndex !== -1) {
                result = str.slice(startIndex, endIndex + 1);
            }
        }
        return result;
    };
}

Abaixo estão as traduções de

• inteiro para palavra
• flutuar para a palavra
• dinheiro para palavra

Os casos de teste estão na parte inferior

var ONE_THOUSAND = Math.pow(10, 3);
var ONE_MILLION = Math.pow(10, 6);
var ONE_BILLION = Math.pow(10, 9);
var ONE_TRILLION = Math.pow(10, 12);
var ONE_QUADRILLION = Math.pow(10, 15);
var ONE_QUINTILLION = Math.pow(10, 18);

function integerToWord(integer) {
  var prefix = '';
  var suffix = '';

  if (!integer){ return "zero"; }
  
  if(integer < 0){
    prefix = "negative";
    suffix = integerToWord(-1 * integer);
    return prefix + " " + suffix;
  }
  if(integer <= 90){
    switch (integer) {
      case integer < 0:
        prefix = "negative";
        suffix = integerToWord(-1 * integer);
        return prefix + " "  + suffix;
      case 1: return "one";
      case 2: return "two";
      case 3: return "three";
      case 4:  return "four";
      case 5: return "five";
      case 6: return "six";
      case 7: return "seven";
      case 8: return "eight";
      case 9: return "nine";
      case 10: return "ten";
      case 11: return "eleven";
      case 12: return "twelve";
      case 13: return "thirteen";
      case 14: return "fourteen";
      case 15: return "fifteen";
      case 16: return "sixteen";
      case 17: return "seventeen";
      case 18: return "eighteen";
      case 19: return "nineteen";
      case 20: return "twenty";
      case 30: return "thirty";
      case 40: return "forty";
      case 50: return "fifty";
      case 60: return "sixty";
      case 70: return "seventy";
      case 80: return "eighty";
      case 90: return "ninety";
      default: break;
    }
  }

  if(integer < 100){
    prefix = integerToWord(integer - integer % 10);
    suffix = integerToWord(integer % 10);
    return prefix + "-"  + suffix;
  }

  if(integer < ONE_THOUSAND){
    prefix = integerToWord(parseInt(Math.floor(integer / 100), 10) )  + " hundred";
    if (integer % 100){ suffix = " and "  + integerToWord(integer % 100); }
    return prefix + suffix;
  }

  if(integer < ONE_MILLION){
    prefix = integerToWord(parseInt(Math.floor(integer / ONE_THOUSAND), 10))  + " thousand";
    if (integer % ONE_THOUSAND){ suffix = integerToWord(integer % ONE_THOUSAND); }
  }
  else if(integer < ONE_BILLION){
    prefix = integerToWord(parseInt(Math.floor(integer / ONE_MILLION), 10))  + " million";
    if (integer % ONE_MILLION){ suffix = integerToWord(integer % ONE_MILLION); }
  }
  else if(integer < ONE_TRILLION){
    prefix = integerToWord(parseInt(Math.floor(integer / ONE_BILLION), 10))  + " billion";
    if (integer % ONE_BILLION){ suffix = integerToWord(integer % ONE_BILLION); }
  }
  else if(integer < ONE_QUADRILLION){
    prefix = integerToWord(parseInt(Math.floor(integer / ONE_TRILLION), 10))  + " trillion";
    if (integer % ONE_TRILLION){ suffix = integerToWord(integer % ONE_TRILLION); }
  }
  else if(integer < ONE_QUINTILLION){
    prefix = integerToWord(parseInt(Math.floor(integer / ONE_QUADRILLION), 10))  + " quadrillion";
    if (integer % ONE_QUADRILLION){ suffix = integerToWord(integer % ONE_QUADRILLION); }
  } else {
    return '';
  }
  return prefix + " "  + suffix;
}

function moneyToWord(value){
  var decimalValue = (value % 1);
  var integer = value - decimalValue;
  decimalValue = Math.round(decimalValue * 100);
  var decimalText = !decimalValue? '': integerToWord(decimalValue) + ' cent' + (decimalValue === 1? '': 's');
  var integerText= !integer? '': integerToWord(integer) + ' dollar' + (integer === 1? '': 's');
  return (
    integer && !decimalValue? integerText:
    integer && decimalValue? integerText + ' and ' + decimalText:
    !integer && decimalValue? decimalText:
    'zero cents'
  );
}

function floatToWord(value){
  var decimalValue = (value % 1);
  var integer = value - decimalValue;
  decimalValue = Math.round(decimalValue * 100);
  var decimalText = !decimalValue? '':
    decimalValue < 10? "point o' " + integerToWord(decimalValue):
    decimalValue % 10 === 0? 'point ' + integerToWord(decimalValue / 10):
    'point ' + integerToWord(decimalValue);
  return (
    integer && !decimalValue? integerToWord(integer):
    integer && decimalValue? [integerToWord(integer),  decimalText].join(' '):
    !integer && decimalValue? decimalText:
    integerToWord(0)
  );
}

// test
(function(){
  console.log('integerToWord ==================================');
  for(var i = 0; i < 101; ++i){
    console.log('%s=%s', i, integerToWord(i));
  }
  console.log('floatToWord ====================================');
  i = 131;
  while(i--){
    console.log('%s=%s', i / 100, floatToWord(i / 100));
  }
  console.log('moneyToWord ====================================');
  for(i = 0; i < 131; ++i){
    console.log('%s=%s', i / 100, moneyToWord(i / 100));
  }
}());

Muitas respostas boas. Eu precisava do meu para o sistema de numeração indiano (sul da Ásia). Modifiquei um dos códigos acima - anexando aqui, caso outra pessoa precise. No sistema de numeração indiano, os grupos após o milhar têm 2 dígitos, não 3, como no sistema ocidental.

var IS_SOUTH_ASIAN = true;
function int_to_words(int) {
  if (int === 0) return 'zero';

  var ONES_WORD  = ['','one','two','three','four','five','six','seven','eight','nine','ten','eleven','twelve','thirteen','fourteen','fifteen','sixteen','seventeen','eighteen','nineteen'];
  var TENS_WORD  = ['','','twenty','thirty','fourty','fifty','sixty','seventy','eighty','ninety'];
  var SCALE_WORD_WESTERN = ['','thousand','million','billion','trillion','quadrillion','quintillion','sextillion','septillion','octillion','nonillion'];
  var SCALE_WORD_SOUTH_ASIAN = ['','thousand','lakh','crore','arab','kharab','neel','padma','shankh','***','***'];

  var GROUP_SIZE = (typeof IS_SOUTH_ASIAN != "undefined" && IS_SOUTH_ASIAN) ? 2 : 3;
  var SCALE_WORD = (typeof IS_SOUTH_ASIAN != "undefined" && IS_SOUTH_ASIAN) ? SCALE_WORD_SOUTH_ASIAN : SCALE_WORD_WESTERN;


  // Return string of first three digits, padded with zeros if needed
  function get_first_3(str) {
    return ('000' + str).substr(-(3));
  }
  function get_first(str) { //-- Return string of first GROUP_SIZE digits, padded with zeros if needed, if group size is 2, make it size 3 by prefixing with a '0'
    return (GROUP_SIZE == 2 ? '0' : '') + ('000' + str).substr(-(GROUP_SIZE));
  }


  // Return string of digits with first three digits chopped off
  function get_rest_3(str) {
    return str.substr(0, str.length - 3);
  }
  function get_rest(str) { // Return string of digits with first GROUP_SIZE digits chopped off
    return str.substr(0, str.length - GROUP_SIZE);
  }

  // Return string of triplet convereted to words
  function triplet_to_words(_3rd, _2nd, _1st) {
    return  (_3rd == '0' ? '' : ONES_WORD[_3rd] + ' hundred ') + 
            (_1st == '0' ? TENS_WORD[_2nd] : TENS_WORD[_2nd] && TENS_WORD[_2nd] + '-' || '') + 
            (ONES_WORD[_2nd + _1st] || ONES_WORD[_1st]);  //-- 1st one returns one-nineteen - second one returns one-nine
  }

  // Add to result, triplet words with scale word
  function add_to_result(result, triplet_words, scale_word) {
    return triplet_words ? triplet_words + (scale_word && ' ' + scale_word || '') + ' ' + result : result;
  }

  function recurse (result, scaleIdx, first, rest) {
    if (first == '000' && rest.length === 0) return result;
    var newResult = add_to_result (result, triplet_to_words (first[0], first[1], first[2]), SCALE_WORD[scaleIdx]);
    return recurse (newResult, ++scaleIdx, get_first(rest), get_rest(rest));
  }

  return recurse ('', 0, get_first_3(String(int)), get_rest_3(String(int)));
}

embora este sistema use um loop for, ele usa o inglês dos EUA e é rápido, preciso e expansível (você pode adicionar valores infinitos à var "th" e eles serão incluídos).

Esta função captura os 3 grupos de números ao contrário para obter os grupos de números onde um ,normalmente os separaria na forma numérica. Em seguida, cada grupo de três números é adicionado a uma matriz com a forma de palavra apenas dos 3 números (ex: cento e vinte e três). Em seguida, ele pega essa nova lista de array e a reverte novamente, enquanto adiciona o thvar do mesmo índice ao final da string.

var ones = ['','one ','two ','three ','four ', 'five ','six ','seven ','eight ','nine ','ten ','eleven ','twelve ','thirteen ','fourteen ','fifteen ','sixteen ','seventeen ','eighteen ','nineteen '];
var tens = ['', '', 'twenty ','thirty ','forty ','fifty ', 'sixty ','seventy ','eighty ','ninety ', 'hundred '];
var th = ['', 'thousand ','million ','billion ', 'trillion '];

function numberToWord(number){
  var text = "";
  var size = number.length;

  var textList = [];
  var textListCount = 0;

  //get each 3 digit numbers
  for(var i = number.length-1; i >= 0; i -= 3){
    //get 3 digit group
    var num = 0;
    if(number[(i-2)]){num += number[(i-2)];}
    if(number[(i-1)]){num += number[(i-1)];}
    if(number[i]){num += number[i];}

    //remove any extra 0's from begining of number
    num = Math.floor(num).toString();

    if(num.length == 1 || num < 20){
      //if one digit or less than 20
      textList[textListCount] = ones[num];
    }else if(num.length == 2){
      //if 2 digits and greater than 20
      textList[textListCount] = tens[num[0]]+ones[num[1]];
    }else if(num.length == 3){
      //if 3 digits
      textList[textListCount] = ones[num[0]]+tens[10]+tens[num[1]]+ones[num[2]];
    }

    textListCount++;

  }

  //add the list of 3 digit groups to the string
  for(var i = textList.length-1; i >= 0; i--){
    if(textList[i] !== ''){text += textList[i]+th[i];} //skip if the number was 0
  }

  return text;
}

Converta dígitos em palavras em francês usando JavaScript e html - palavras originais em francês

    <html>
        <head>
            <title>Number to word</title>

            <script>
                function toWords() {
                    var s = document.getElementById('value').value;
                    var th = ['','mille','million', 'milliard','billion'];
                    var dg = ['zéro','un','deux','trois','quatre', 'cinq','six','sept','huit','neuf'];
                    var tn = 

['dix','onze','douze','treize', 'quatorze','quinze','seize', 'dix-sept','dix-huit','dix-neuf'];
                var tw = ['vingt','trente','quarante','cinquante', 'soixante','soixante-dix','quatre-vingt','quatre-vingt-dix'];
                s = s.toString();
                s = s.replace(/[\, ]/g,'');
                if (s != parseFloat(s)) return 'not a number';
                var x = s.indexOf('.');
                if (x == -1)
                    x = s.length;
                if (x > 15)
                    return 'too big';
                var n = s.split(''); 
                var str = '';
                var sk = 0;
                for (var i=0;   i < x;  i++) {
                    if ((x-i)%3==2) { 
                        if (n[i] == '1') {

                            str += tn[Number(n[i+1])] + ' ';
                            i++;
                            sk=1;
                        } else if (n[i]!=0) { 
                            if(s!=21 && s!=31 && s!=41 && s!=51 && s!=61 && s!=71 && s!=72 && s!=73 && s!=74 && s!=75 && s!=76 && s!=100 && s!=91 && s!=92 && s!=93 && s!=94 && s!=95 && s!=96){
                            if(s==20 || s==30 || s==40 || s==50 || s==60 || s==70 || s==80 || s==90){
                            str += tw[n[i]-2] + ' ';} // for not to display hyphens for 20,30...90 
                            else{
                            str += tw[n[i]-2] + '-';}
                            sk=1;
                            }
                        }
                    } else if (n[i]!=0) {
                        if(s!=21 && s!=31 && s!=41 && s!=51 && s!=61 && s!=71 && s!=72 && s!=73 && s!=74 && s!=75 && s!=76 && s!=100 && s!=91 && s!=92 && s!=93 && s!=94 && s!=95 && s!=96){

                        str += dg[n[i]] +' ';
                        if ((x-i)%3==0) str += 'hundert ';  // for start from 101 - 

                        sk=1;
                        }
                    }
                    if ((x-i)%3==1) {
                        if(s!=21 && s!=31 && s!=41 && s!=51 && s!=61 && s!=71 && s!=72 && s!=73 && s!=74 && s!=75 && s!=76 && s!=100 && s!=91 && s!=92 && s!=93 && s!=94 && s!=95 && s!=96){
                        if (sk)
                            str += th[(x-i-1)/3] + ' ';
                        sk=0;
                        }
                    }
                }

                if (x != s.length) {
                    var y = s.length;
                    //str += 'point ';
                    //for (var i=x+1; i<y; i++)
                    //  str += dg[n[i]] +' ';
                    str += 'virgule ';
                     var counter=0;
                     for (var i=x+1; i<y; i++){
                        if ((y-i)%3==2) { 
                                            if (n[i] == '1') {
                                                            str += tn[Number(n[i+1])] + ' ';
                                                            i++;
                                                            counter=1;
                                            } else if (n[i]!=0) {
                                                            str += tw[n[i]-2] + '-';
                                                            counter=1;
                                            }
                                        }else if (n[i]!=0) { // 0235
                                            str += dg[n[i]] +' ';
                                        }
                     }

                }

                if (s!=21 && s!=31 && s!=41 && s!=51 && s!=61 && s!=71 && s!=72 && s!=73 && s!=74 && s!=75 && s!=76 && s!=100 && s!=91 && s!=92 && s!=93 && s!=94 && s!=95 && s!=96){
                document.getElementById("demo").innerHTML = str.replace(/\s+/g,' ')

                }
                else if (s==21){
                str = 'vingt-et-un'
                document.getElementById("demo").innerHTML = str;
                }//alert(str.replace(/\s+/g,' '));
                else if (s==31){
                str = 'trente-et-un'
                document.getElementById("demo").innerHTML = str;}
                else if (s==41){
                str = 'quarante-et-un'
                document.getElementById("demo").innerHTML = str;}
                else if (s==51){
                str = 'cinquante-et-un'
                document.getElementById("demo").innerHTML = str;}
                else if (s==61){
                str = 'soixante-et-un'
                document.getElementById("demo").innerHTML = str;}
                else if (s==71){
                str = 'soixante-et-onze'
                document.getElementById("demo").innerHTML = str;}
                else if (s==72){
                str = 'soixante-douze'
                document.getElementById("demo").innerHTML = str;}
                else if (s==73){
                str = 'soixante-treize'
                document.getElementById("demo").innerHTML = str;}
                else if (s==74){
                str = 'soixante-quatorze'
                document.getElementById("demo").innerHTML = str;}
                else if (s==75){
                str = 'soixante-quinze'
                document.getElementById("demo").innerHTML = str;}
                else if (s==76){
                str = 'soixante-seize'
                document.getElementById("demo").innerHTML = str;}
                else if (s==100){
                str = 'cent'
                document.getElementById("demo").innerHTML = str;}
                else if (s==91){
                str = 'quatre-vingt-onze'
                document.getElementById("demo").innerHTML = str;}
                else if (s==92){
                str = 'quatre-vingt-douze'
                document.getElementById("demo").innerHTML = str;}
                else if (s==93){
                str = 'quatre-vingt-treize'
                document.getElementById("demo").innerHTML = str;}
                else if (s==94){
                str = 'quatre-vingt-quatorze'
                document.getElementById("demo").innerHTML = str;}   
                else if (s==95){
                str = 'quatre-vingt-quinze'
                document.getElementById("demo").innerHTML = str;}   
                else if (s==96){
                str = 'quatre-vingt-seize'
                document.getElementById("demo").innerHTML = str;}               
            }
        </script>
    </head>
    <body>
        <p>Enter only numbers (max 15 digits) : </p>
        <input type="text" name="value" id='value' /><br>
        <input type="button" value="submit" onclick="toWords()" />
        <p id="demo"></p>
        <p id="demo1"></p>
    </body>
</html> 

Você pode verificar minha versão no github. Não é tão difícil assim. Eu testo isso para os números entre 0 e 9999, mas você pode estender a matriz se quiser dígitos em palavras

Experimente este código com um JavaScript compatível com a moeda turca

function dene() {
         var inpt = document.getElementById("tar1").value;
         var spt = inpt.split('');
         spt.reverse();

         var tek = ["", "Bir", "İki", "Üç", "Dört", "Beş", "Altı", "Yedi", "Sekiz", "Dokuz"];
         var onlu = ["", "On", "Yirmi", "Otuz", "Kırk", "Elli", "Atmış", "Yetmiş", "Seksen", "Doksan"];
         var Yuz = ["", "Yüz", "İkiYüz", "Üçyüz", "DörtYüz", "BeşYüz", "AltıYüz", "YediYüz", "SekizYüz", "DokuzYüz"];
         var ska = ["", "", "", "", "Bin", "Milyon", "Milyar", "Trilyon", "Katrilyon", "Kentilyon"];
         var i, j;
         var bas3 = "";
         var bas6 = "";
         var bas9 = "";
         var bas12 = "";
         var total;

               for(i = 0; i < 1; i++) {

                      bas3 += Yuz[spt[i+2]] + onlu[spt[i+1]] + tek[spt[i]];
                      bas6 += Yuz[spt[i+5]] + onlu[spt[i+4]] + tek[spt[i+3]] + ska[4];
                      bas9 += Yuz[spt[i+8]] + onlu[spt[i+7]] + tek[spt[i+6]] + ska[5];
                      bas12 += Yuz[spt[i+11]] + onlu[spt[i+10]] + tek[spt[i+9]] + ska[6];


                   if(inpt.length < 4) {
                       bas6 = '';
                       bas9 = '';
                   }
                   if(inpt.length > 6 && inpt.slice(5, 6) == 0) {
                     bas6 = bas6.replace(/Bin/g, '');
                   }
                   if(inpt.length < 7) {
                       bas9 = '';
                   } 
                   if(inpt.length > 9 && inpt.slice(1,3) == 000){
                       bas9 = bas9.replace(/Milyon/g, '');
                   }

                   if(inpt.length < 10) {
                    bas12 = '';
                 }
             }

         total = bas12 + bas9 + bas6 + bas3;
         total = total.replace(NaN, '');
         total = total.replace(undefined, '');

        document.getElementById('demo').innerHTML = 
            total;


     }

Isso também é uma resposta à excelente postagem de naomik ! Infelizmente não tenho representante para postar no local correto, mas deixo aqui caso possa ajudar alguém.

Se você precisa de um formulário escrito em inglês britânico, é necessário fazer algumas adaptações ao código. O inglês britânico difere do americano em alguns aspectos. Basicamente, você precisa inserir a palavra 'e' em dois lugares específicos.

1. Depois de cem presumindo que há dezenas e unidades. Por exemplo, cento e dez. Mil e dezessete. NÃO mil e cem.
2. Em certas arestas, após um mil, um milhão, um bilhão etc . quando não há unidades menores. Por exemplo, mil e dez. Um milhão e quarenta e quatro. NÃO Um milhão e mil.

A primeira situação pode ser resolvida verificando 10s e 1s no método makeGroup e anexando 'e' quando eles existirem.

makeGroup = ([ones,tens,huns]) => {
var adjective = this.num(ones) ? ' hundred and ' : this.num(tens) ? ' hundred and ' : ' hundred';
return [
  this.num(huns) === 0 ? '' : this.a[huns] + adjective,
  this.num(ones) === 0 ? this.b[tens] : this.b[tens] && this.b[tens] + '-' || '',
  this.a[tens+ones] || this.a[ones]
].join('');

};

O segundo caso é mais complicado. É equivalente a

• adicione 'e' a 'um milhão, mil' ou 'um bilhão' se o número antepenúltimo for zero. por exemplo

1.100, 0 57 um milhão cento e cinquenta e sete. 5.000, 0 06 cinco milhões e seis

Acho que isso poderia ser implementado no código do @naomik através do uso de uma função de filtro, mas não consegui descobrir como. No final, decidi percorrer de forma hackeada o array de palavras retornado e usar indexOf para procurar instâncias em que a palavra 'cem' estava faltando no elemento final.

Acabei de escrever paisa.js para fazer isso, e ele lida com lakhs e crores corretamente também, pode dar uma olhada. O núcleo se parece um pouco com isto:

const regulars = [
  {
    1: 'one', 2: 'two', 3: 'three', 4: 'four', 5: 'five', 6: 'six', 7: 'seven', 8: 'eight', 9: 'nine'
  },
  {
    2: 'twenty', 3: 'thirty', 4: 'forty', 5: 'fifty', 6: 'sixty', 7: 'seventy', 8: 'eighty', 9: 'ninety'
  }
]

const exceptions = {
  10: 'ten',
  11: 'eleven',
  12: 'twelve',
  13: 'thirteen',
  14: 'fourteen',
  15: 'fifteen',
  16: 'sixteen',
  17: 'seventeen',
  18: 'eighteen',
  19: 'nineteen'
}

const partInWords = (part) => {
  if (parseInt(part) === 0) return
  const digits = part.split('')
  const words = []
  if (digits.length === 3) {
    words.push([regulars[0][digits.shift()], 'hundred'].join(' '))
  }
  if (exceptions[digits.join('')]) {
    words.push(exceptions[digits.join('')])
  } else {
    words.push(digits.reverse().reduce((memo, el, i) => {
      memo.unshift(regulars[i][el])
      return memo
    }, []).filter(w => w).join(' '))
  }
  return words.filter(w => w.trim().length).join(' and ')
}

Minha solução é baseada na solução de Juan Gaitán para moeda indiana, funciona até crores.

function valueInWords(value) {
    let ones = ['', 'one', 'two', 'three', 'four',
            'five', 'six', 'seven', 'eight', 'nine',
            'ten', 'eleven', 'twelve', 'thirteen', 'fourteen',
            'fifteen', 'sixteen', 'seventeen', 'eighteen', 'nineteen'];   
    let tens = ['twenty','thirty', 'forty','fifty', 'sixty', 'seventy', 'eighty', 'ninety'];
    let digit = 0;   
    if (value < 20) return ones[value];   
    if (value < 100) {     
        digit = value % 10; //remainder     
        return tens[Math.floor(value/10)-2] + " " + (digit > 0 ? ones[digit] : "");   
    }
    if (value < 1000) {    
         return ones[Math.floor(value/100)] + " hundred " + (value % 100 > 0 ? valueInWords(value % 100) : "");   
    }   
    if (value < 100000) {     
        return valueInWords(Math.floor(value/1000)) + " thousand " + (value % 1000 > 0 ? valueInWords(value % 1000) : "");   
    }   
    if (value < 10000000) {     
        return valueInWords(Math.floor(value/100000)) + " lakh " + (value % 100000 > 0 ? valueInWords(value % 100000) : "");   
    }   
    return valueInWords(Math.floor(value/10000000)) + " crore " + (value % 10000000 > 0 ? valueInWords(value % 10000000) : ""); 
}

Para quem procura convenções de nomenclatura imperial / inglês.

Com base na resposta de @Salman

var a = ['','one ','two ','three ','four ', 'five ','six ','seven ','eight ','nine ','ten ','eleven ','twelve ','thirteen ','fourteen ','fifteen ','sixteen ','seventeen ','eighteen ','nineteen '];
var b = ['', '', 'twenty','thirty','forty','fifty', 'sixty','seventy','eighty','ninety'];

function inWords (num) {
    if ((num = num.toString()).length > 12) return 'overflow';
    n = ('00000000000' + num).substr(-12).match(/^(\d{3})(\d{3})(\d{3})(\d{1})(\d{2})$/);
    if (!n) return; var str = '';
    str += (n[1] != 0) ? (Number(n[1]) > 99 ? this.a[Number(n[1][0])] + 'hundred ' : '') + (a[Number(n[1])] || b[n[1][1]] + ' ' + a[n[1][2]]) + 'billion ' : '';
    str += (n[2] != 0) ? (Number(n[2]) > 99 ? this.a[Number(n[2][0])] + 'hundred ' : '') + (a[Number(n[2])] || b[n[2][1]] + ' ' + a[n[2][2]]) + 'million ' : '';
    str += (n[3] != 0) ? (Number(n[3]) > 99 ? this.a[Number(n[3][0])] + 'hundred ' : '') + (a[Number(n[3])] || b[n[3][1]] + ' ' + a[n[3][2]]) + 'thousand ' : '';
    str += (n[4] != 0) ? (a[Number(n[4])] || b[n[4][0]] + ' ' + a[n[4][1]]) + 'hundred ' : '';
     str += (Number(n[5]) !== 0) ? ((str !== '') ? 'and ' : '') +
                (this.a[Number(n[5])] || this.b[n[5][0]] + ' ' +
                    this.a[n[5][1]]) + '' : '';
    return str;
}

document.getElementById('number').onkeyup = function () {
    document.getElementById('words').innerHTML = inWords(document.getElementById('number').value);
};

<span id="words"></span>
<input id="number" type="text" />

Abordagem mais limpa e fácil que veio à mente:

const numberText = {
  1: 'one',
  2: 'two',
  3: 'three',
  4: 'four',
  5: 'five',
  6: 'six',
  7: 'seven',
  8: 'eight',
  9: 'nine',
  10: 'ten',
  11: 'eleven',
  12: 'twelve',
  13: 'thirteen',
  14: 'fourteen',
  15: 'fifteen',
  16: 'sixteen',
  17: 'seventeen',
  18: 'eighteen',
  19: 'nineteen',
  20: 'twenty',
  30: 'thirty',
  40: 'forty',
  50: 'fifty',
  60: 'sixty',
  70: 'seventy',
  80: 'eighty',
  90: 'ninety',
  100: 'hundred',
  1000: 'thousand',
}

const numberValues = Object.keys(numberText)
  .map((val) => Number(val))
  .sort((a, b) => b - a)

const convertNumberToEnglishText = (n) => {
  if (n === 0) return 'zero'
  if (n < 0) return 'negative ' + convertNumberToEnglishText(-n)

  let num = n
  let text = ''

  for (const numberValue of numberValues) {
    const count = Math.trunc(num / numberValue)

    if (count < 1) continue

    if (numberValue >= 100) text += convertNumberToEnglishText(count) + ' '

    text += numberText[numberValue] + ' '
    num -= count * numberValue
  }

  if (num !== 0) throw Error('Something went wrong!')

  return text.trim()
}

Função que funcionará com valores decimais também

function amountToWords(amountInDigits){
    // American Numbering System
    var th = ['','thousand','million', 'billion','trillion'];

    var dg = ['zero','one','two','three','four', 'five','six','seven','eight','nine'];
    var tn = ['ten','eleven','twelve','thirteen', 'fourteen','fifteen','sixteen', 'seventeen','eighteen','nineteen'];
    var tw = ['twenty','thirty','forty','fifty', 'sixty','seventy','eighty','ninety'];
    function toWords(s){
      s = s.toString();
      s = s.replace(/[\, ]/g,'');
      if (s != parseFloat(s))
      return 'not a number';
      var x = s.indexOf('.');
      if (x == -1) x = s.length;
      if (x > 15) return 'too big';
      var n = s.split('');
      var str = '';
      var sk = 0;
      for (var i=0; i < x; i++){
        if ((x-i)%3==2){
          if (n[i] == '1') {
            str += tn[Number(n[i+1])] + ' ';
            i++; sk=1;
          } else if (n[i]!=0) {
              str += tw[n[i]-2] + ' ';sk=1;
            }
          } else if (n[i]!=0) {
            str += dg[n[i]] +' ';
            if ((x-i)%3==0)
            str += 'hundred ';
            sk=1;
          } if ((x-i)%3==1) {
            if (sk) str += th[(x-i-1)/3] + ' ';sk=0;
          }
        }
        if (x != s.length) {
          var y = s.length;
          str += 'point ';
          for (var i=x+1; i<y; i++) str += dg[n[i]] +' ';
        }
        return str.replace(/\s+/g,' ');
      }

      return toWords(amountInDigits);
  }

<input type="text" name="number" placeholder="Number OR Amount" onkeyup="word.innerHTML=amountToWords(this.value)" />
<div id="word"></div>

 var units = ["", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine"];
var tens = ["", "", "twenty", "thirty", "forty", "fifty", "sixty", "seventy", "eighty", "ninety"];



function convert7digitIntoWords(num) {
    var remainder = num % 1000000
    var hun = num - remainder;
    var div = Math.floor(num / 100000);
    if (remainder !== 0)
        return (convert2digitIntoWords(div) + " lakhs " + convert5digitIntoWords(remainder % 100000))
    else
        return (convert2digitIntoWords(div) + " lakhs ")
}

function convert6digitIntoWords(num) {
    var remainder = num % 100000
    var hun = num - remainder;
    var div = Math.floor(num / 100000);
    if (remainder !== 0)
        return (units[div] + " lakh " + convert5digitIntoWords(remainder))
    else
        return (units[div] + " lakh ")
}

function convert5digitIntoWords(num) {
    var remainder = num % 10000
    var hun = num - remainder;
    var div = Math.floor(num / 1000);
    if (remainder !== 0)
        return (convert2digitIntoWords(div) + " thousand " + convert3digitIntoWords(remainder % 1000))
    else
        return (convert2digitIntoWords(div) + " thousand")
}

function convert4digitIntoWords(num) {
    var remainder = num % 1000
    var hun = num - remainder;
    var div = Math.floor(num / 1000);
    if (remainder !== 0)
        return (units[div] + " thousand " + convert3digitIntoWords(remainder))
    else
        return (units[div] + " thousand")
}


function convert3digitIntoWords(num) {
    var remainder = num % 100
    var hun = num - remainder;
    var div = Math.floor(num / 100);
    if (remainder !== 0)
        return (units[div] + " hundred " + convert2digitIntoWords(remainder))
    else
        return (units[div] + " hundred ")
}

function convert2digitIntoWords(num) {
    var remainder = num % 10;
    var div = Math.floor(num / 10);
    return (tens[div] + " " + convertNumIntoWords(remainder));
}

function convertNumIntoWords(num) {

    switch (("" + num).length) {
        case 1:
            return units[num];
        case 2:
            return convert2digitIntoWords(num);
        case 3:
            return convert3digitIntoWords(num)
        case 4:
            return convert4digitIntoWords(num)
        case 5:
            return convert5digitIntoWords(num)
        case 6:
            return convert6digitIntoWords(num)
        case 7:
            return convert7digitIntoWords(num)
        default:
            return "cannot be converted"
    }
}

console.log(convertNumIntoWords(3445125));