Generate a random number between specific range in JavaScript

This post will discuss how to generate a random number between the specified range in JavaScript.

1. Using `Math.random()` function

The Math.random() function returns a floating-point, pseudorandom number greater than or equal to 0 and less than 1, which you can then scale to your desired range.

The following code generates a random number between min and max.

// Returns a random number between `min` and `max` (both inclusive)

function random(min, max) {

return Math.floor(Math.random() * (max - min + 1)) + min;

}

var rand = random(2, 4);

console.log(rand);

// Expected Output: 2, 3, or 4

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This works as Math.random() generates a pseudorandom value between 0 (inclusive) and 1 (exclusive). When multiplied by (max - min) + 1, the lower bound remains 0, but the upper bound becomes (max - min, max - min + 1). Now, after calling Math.floor(), the range becomes [0, max – min] and on adding min, the range becomes [min, max].

2. Using Underscore/Lodash Library

Another alternative is to use the _.random method from underscore or lodash library. It generates a random integer between the specified lower and upper bounds, both inclusive.

var _ = require('underscore');

// Returns a random number between min and max

function random(min, max) {

return _.random(min, max);

}

var rand = random(2, 4);

console.log(rand);

// Expected Output: 2, 3, or 4

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If only a single argument is specified, _.random will generate a number between 0 and that number, both inclusive.

var _ = require('underscore');

var n = 3;

var rand = _.random(n);

console.log(rand);

// Expected Output: 0, 1, 2, or 4

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That’s all about generating a random number between specified ranges in JavaScript.

Generate a random number between specific range in JavaScript

1. Using Math.random() function

2. Using Underscore/Lodash Library

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1. Using `Math.random()` function