3 Neat toString() Tricks in JavaScript

Most JavaScript objects and primitive values have a toString() function that converts the value to a string. Different values have different toString() methods, and some toString() methods have cool surprises. Here's 3:

1) Numbers have a toString() function that supports different bases

Converting decimal to binary in JavaScript is easy, because JavaScript numbers have a toString() function that takes a radix parameter that specifies which base to use.

let x = 42;

x.toString(2); // '101010'

x.toString(16); // '2a', hexadecimal!

2) Encode data as base64 using Node.js Buffers

Node buffers have a toString() function that takes an encoding parameter. Calling toString('base64') converts the buffer into a base64 string, which is handy if you need to convert a file into base64 for email attachments.

const fs = require('fs');

const buf = fs.readFileSync('./package.json');
buf.toString('base64'); // 'ewogICJuYW1lIjog...'

3) Custom Tags for Objects

Objects' toString() is not very useful by default: the output is just [object Object]. However, you can make this output slightly more useful by setting the object's Symbol.toStringTag:

const obj = {};

obj[Symbol.toStringTag] = 'Test';
obj.toString(); // '[object Test]'