How to replace the first given number of characters of a string with another character in JavaScript

In this Article we will go through how to replace the first given number of characters of a string with another character 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 mask = (str, num, mask) => `${str}`.slice(num).padStart(`${str}`.length, mask);

mask(1234567890, 3, '*');       // ***4567890