(function () {
"use strict";
var atob = require('atob');
var b64 = "SGVsbG8sIFdvcmxkIQ==";
var bin = atob(b64);
console.log(bin); // "Hello, World!"
}());
const encodedData = btoa('Hello, world'); // encode a string
const decodedData = atob(encodedData); // decode the stringThe atob() and btoa() methods allow authors to transform content to and from the base64 encoding.
In these APIs, for mnemonic purposes, the "b" can be considered to stand for "binary", and the "a" for "ASCII". In practice, though, for primarily historical reasons, both the input and output of these functions are Unicode strings.
From : http://www.w3.org/TR/html/webappapis.html#atob