Regex corresponde a palavras inteiras apenas JS
let string = "Hello world"; // you can use .toLowerCase() to check only in lower
let match = "world"; // word to match
let regex = new RegExp('\\b('+match+')\\b');
console.log('true for no match, false for match');
console.log(string.match(regex) == null); //.match() returns array of words found
// true for no match, false for match
// false
L'homme habile