Javascript – Generate random number between two numbers in JavaScript

javascriptrandom

Is there a way to generate a random number in a specified range (e.g. from 1 to 6: 1, 2, 3, 4, 5, or 6) in JavaScript?

Best Answer

function randomIntFromInterval(min, max) { // min and max included 
  return Math.floor(Math.random() * (max - min + 1) + min)
}

const rndInt = randomIntFromInterval(1, 6)
console.log(rndInt)

What it does "extra" is it allows random intervals that do not start with 1. So you can get a random number from 10 to 15 for example. Flexibility.

Related Solutions

Javascript – How to create a GUID / UUID

[Edited 2021-10-16 to reflect latest best-practices for producing RFC4122-complaint UUIDs]

Most readers here will want to use the uuid module. It is well-tested and supported.

The crypto.randomUUID() function is an emerging standard that is supported in Node.js and an increasing number of browsers.

If neither of those work for you, there is this method (based on the original answer to this question):

function uuidv4() {
  return ([1e7]+-1e3+-4e3+-8e3+-1e11).replace(/[018]/g, c =>
    (c ^ crypto.getRandomValues(new Uint8Array(1))[0] & 15 >> c / 4).toString(16)
  );
}

console.log(uuidv4());

Note: The use of any UUID generator that relies on Math.random() is strongly discouraged (including snippets featured in previous versions of this answer) for reasons best-explained here. TL;DR: Math.random()-based solutions do not provide good uniqueness guarantees.

Javascript – How to check if an array includes a value in JavaScript

Modern browsers have Array#includes, which does exactly that and is widely supported by everyone except IE:

console.log(['joe', 'jane', 'mary'].includes('jane')); //true

You can also use Array#indexOf, which is less direct, but doesn't require polyfills for outdated browsers.

console.log(['joe', 'jane', 'mary'].indexOf('jane') >= 0); //true

Many frameworks also offer similar methods:

jQuery: $.inArray(value, array, [fromIndex])
Underscore.js: _.contains(array, value) (also aliased as _.include and _.includes)
Dojo Toolkit: dojo.indexOf(array, value, [fromIndex, findLast])
Prototype: array.indexOf(value)
MooTools: array.indexOf(value)
MochiKit: findValue(array, value)
MS Ajax: array.indexOf(value)
Ext: Ext.Array.contains(array, value)
Lodash: _.includes(array, value, [from]) (is _.contains prior 4.0.0)
Ramda: R.includes(value, array)

Notice that some frameworks implement this as a function, while others add the function to the array prototype.

Best Answer

Related Solutions

Javascript – How to create a GUID / UUID

Javascript – How to check if an array includes a value in JavaScript

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