Generating Random Numbers in JavaScript

Generating Random Numbers in JavaScript

It?s more than Math.random()

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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.floorfunction 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);

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.

Thanks for reading!


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