Generating Random Numbers in JavaScript

It’s more than Math.random()

The Math.random() will generate a pseudo-random floating number (a number with decimals) between 0 (inclusive) and 1 (exclusive).

Here, the random number doesn’t mean that you always get a unique number. It generates the same number only after some interval. The interval here is very long, so you probably won’t get the same number twice.

To generate a random number, we can use:

Math.random(); //0.6140915758927235 may be  you get different value

Defining our own random number function:

function rand(maxLimit = 100) {

   return Math.random() * maxLimit;

}   

rand(10); // 5.500949568251157

To get whole numbers, we can use:

• Math.floor() → to round down
• Math.ceil() → to round up
• Math.round() → to nearest number

// using Math.floor

function rand(maxLimit = 100) {

 let rand = Math.random() * maxLimit;

 return Math.floor(rand);

}

// the above code generates any numbers between 0 to maxLimit-1

To get a random number between two numbers (min included, max excluded):

function rand(min, max) {

  let randomNum = Math.random() * (max - min) + min;

  return Math.floor(randomNum);

}

rand(10, 20);

In the above code, (max-min) + min is just to handle if there is any case when the max is less than the min. In such a case, where max is less than min:

max = 5, min = 10

(max - min) + min  => (5 - 10) + 5  => -5  + 5 => 0

To get random numbers including min and max element, we can change Math.floor to Math.round :

function rand(min, max) {

   let randomNum = Math.random() * (max - min) + min;

   return Math.round(randomNum);

}

rand(10, 20);

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Generating Random Hex Colours

We know that hex colours have 1–9 and a-f .

To generate random colours:

• Store hex values on array
• Use math.rand to get index
• Create a color string of length six or three.

https://gist.github.com/Jagathishrex/13a7dab8cff2e9e904b5948bd1eaa35b#file-random_color-js

Thanks for reading!