How to prefix an integer with zeros in JavaScript

In this Article we will go through how to prefix an integer with zeros only using single line of code in JavaScript. This is a one-line JavaScript code snippet that uses one of the most popular ES6 features => Arrow Function.

Let's define this short function:

const prefixWithZeros = (number, length) => (number / Math.pow(10, length)).toFixed(length).substr(2);

const prefixWithZeros = (number, length) => `${Array(length).join('0')}${number}`.slice(-length);

const prefixWithZeros = (number, length) => String(number).padStart(length, '0');

prefixWithZeros(42, 5);     // '00042'