How to Base64-Encode a String in Node.js?

The easiest way to encode a string to base64 in Node.js is to use the built-in Buffer object. For example, you can achieve this in the following way:

// 1: define the string to be encoded
const str = 'foobar';

// 2: convert string to buffer
const strBuffer = Buffer.from(str);

// 3: convert buffer to Base64-encoded string
const encoded = strBuffer.toString('base64');

console.log(encoded); // 'Zm9vYmFy'

Unlike the btoa() method in JavaScript, this also works with multibyte strings out of the box:

const toBase64 = (str) => Buffer.from(str).toString('base64');

console.log(toBase64('🦊')); // '8J+mig=='
console.log(toBase64('こんにちは')); // '44GT44KT44Gr44Gh44Gv'
console.log(toBase64('foobar')); // 'Zm9vYmFy'

Please note that the Buffer object is within the global scope, which is why you do not need to explicitly import it using "require('buffer').Buffer" for example.

In versions of Node.js below 6.0.0, the syntax "new Buffer(string[, encoding])" was commonly used. However, using the constructor to instantiate a new Buffer object was deprecated starting from Node.js v6.0.0 as it was vulnerable to "Remote Memory Disclosure" attacks. Therefore, you should use Buffer.from() instead.