Originally Posted Here at Dev Community.

In this post, I will be summarising several possible methods for generating a colour randomly in JavaScript. So, Save this article !

As you might be aware of how colours are represented, i.e, Hexadecimal code with a '#' prefix --> #RRGGBB

The code for Black --> #000000 and for white --> #ffffff Hence higher the values, more the colour will be lighter and vice-versa. Here's the different methods:

• Method 1 In this approach, simply take a string of all possible hexadecimal characters, then choose from it randomly and concatenate them to form a 6 digit hex code.

const s = "0123456789ABCDEF";
function getRandomColor() 
{
    let col = "#";
    let temp =0;
    for(let i=0;i<6;++i)
    {
       temp = Math.floor( Math.random() * s.length ); // generates number between 0-15
       col = col + s[temp];
    }
return col;
}

for generating lighter/Darker colours only, we can use sLight or sDark respectively.

const sLight="789ABCDEF";
const sDark="01234567";

• Method 2 Similar to the first one but here instead of predefined string, we can use toString(16) to convert to HexaDecimal.

function getRandomColor(){
    let color = "#";
    for(let i=0;i<6;++i)
        color += (Math.floor( Math.random() * 16 ).toString(16) );
    return color;
}

• Method 3 We can use the following ES6 approach :

const getRandomHex = from => to => () =>
    Math.floor(Math.random() * (to - from) + from).toString(16);

const getRangedRandomColor = from => to => () =>
    `#${[...Array(6)].map(getRandomHex(from)(to)).join("")}`;

const getRandomColor = getRangedRandomColor(0x0)(0xf);
const getRandomColorLight = getRangedRandomColor(0x7)(0xf);
const getRandomColorDark = getRangedRandomColor(0x0)(0x7);

Thanks to @lukeshiru for this one, and you can find the detailed explaination for this in the comments section of my previous article here

• Method 4

function getRandomColor() {
    function c() {
      var hex = Math.floor(Math.random()*256).toString(16);
      return ("0"+String(hex)).substr(-2); // pad with zero
    }
    return "#"+c()+c()+c();
}

substr(-2) means take last two characters of the string.

• Method 5 This one is a great one liner for the same I found on StackOverflow.

  function getRandomColor() {
    return '#'+(Math.random().toString(16)+'00000').slice(2,8);
  }
  

  Well these were some of my picks, if you want to dive in more, you can have a look at this thread on StackOverFlow.

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