Generate a random hex color code in JavaScript

Hex color codes are used everywhere in web development and, oftentimes, you might need to generate a random one on the fly. This can be useful for a variety of purposes, such as generating random colors for a UI, or for testing purposes.
Generating a random hex color code is fairly simple, but requires some math. You can use the Math.random() method to generate a random 24-bit (6 * 4bits) hexadecimal number, then use bit shifting and convert it to an hexadecimal string using Number.prototype.toString() with a base of 16.
As the resulting number might be longer than 6 characters, you can use String.prototype.slice() to extract the first 6 characters. Finally, you can prepend a # to the string to make it a valid hex color code.

const randomHexColorCode = () => {
  let n = (Math.random() * 0xfffff * 1000000).toString(16);
  return '#' + n.slice(0, 6);
};

randomHexColorCode(); // '#e34155'

As the resulting number might be longer than 6 characters, you can use String.prototype.slice() to extract the first 6 characters. Finally, you can prepend a # to the string to make it a valid hex color code.

From 30-seconds-of-code: random-hex-color-code