Get a Random Item from a Javascript Array [Duplicate]

Get a Random Item from a Javascript Array [Duplicate]
var items = Array(523, 3452, 334, 31, ..., 5346);

How do I get random item from items?

8

13 Answers

var item = items[Math.floor(Math.random()*items.length)];
16

Use underscore (or loDash :)):

var randomArray = [
   '#cc0000','#00cc00', '#0000cc'
];

// use _.sample
var randomElement = _.sample(randomArray);

// manually use _.random
var randomElement = randomArray[_.random(randomArray.length-1)];

Or to shuffle an entire array:

// use underscore's shuffle function
var firstRandomElement = _.shuffle(randomArray)[0];
9

1. solution: define Array prototype

Array.prototype.random = function () {
  return this[Math.floor((Math.random()*this.length))];
}

that will work on inline arrays

[2,3,5].random()

and of course predefined arrays

var list = [2,3,5]
list.random()

2. solution: define custom function that accepts list and returns element

function get_random (list) {
  return list[Math.floor((Math.random()*list.length))];
}


get_random([2,3,5])
7

If you really must use jQuery to solve this problem (NB: you shouldn't):

(function($) {
    $.rand = function(arg) {
        if ($.isArray(arg)) {
            return arg[$.rand(arg.length)];
        } else if (typeof arg === "number") {
            return Math.floor(Math.random() * arg);
        } else {
            return 4;  // chosen by fair dice roll
        }
    };
})(jQuery);

var items = [523, 3452, 334, 31, ..., 5346];
var item = jQuery.rand(items);

This plugin will return a random element if given an array, or a value from [0 .. n) given a number, or given anything else, a guaranteed random value!

For extra fun, the array return is generated by calling the function recursively based on the array's length :)

Working demo at

9

Here's yet another way:

function rand(items) {
    // "~~" for a closest "int"
    return items[~~(items.length * Math.random())];
}

Or as recommended below by @1248177:

function rand(items) {
    // "|" for a kinda "int div"
    return items[items.length * Math.random() | 0];
}
9
var random = items[Math.floor(Math.random()*items.length)]

jQuery is JavaScript! It's just a JavaScript framework. So to find a random item, just use plain old JavaScript, for example,

var randomItem = items[Math.floor(Math.random()*items.length)]
var rndval=items[Math.floor(Math.random()*items.length)];
// 1. Random shuffle items
items.sort(function() {return 0.5 - Math.random()})

// 2. Get first item
var item = items[0]

Shorter:

var item = items.sort(function() {return 0.5 - Math.random()})[0];

Even shoter (by José dB.):

let item = items.sort(() => 0.5 - Math.random())[0];
5
var items = Array(523,3452,334,31,...5346);

function rand(min, max) {
  var offset = min;
  var range = (max - min) + 1;

  var randomNumber = Math.floor( Math.random() * range) + offset;
  return randomNumber;
}


randomNumber = rand(0, items.length - 1);

randomItem = items[randomNumber];

credit:

Javascript Function: Random Number Generator

1

If you are using node.js, you can use unique-random-array. It simply picks something random from an array.

An alternate way would be to add a method to the Array prototype:

 Array.prototype.random = function (length) {
       return this[Math.floor((Math.random()*length))];
 }

 var teams = ['patriots', 'colts', 'jets', 'texans', 'ravens', 'broncos']
 var chosen_team = teams.random(teams.length)
 alert(chosen_team)
3
const ArrayRandomModule = {
  // get random item from array
  random: function (array) {
    return array[Math.random() * array.length | 0];
  },

  // [mutate]: extract from given array a random item
  pick: function (array, i) {
    return array.splice(i >= 0 ? i : Math.random() * array.length | 0, 1)[0];
  },

  // [mutate]: shuffle the given array
  shuffle: function (array) {
    for (var i = array.length; i > 0; --i)
      array.push(array.splice(Math.random() * i | 0, 1)[0]);
    return array;
  }
}
2
David Miller
Author

David Miller

David Miller brings 15 years of experience in global economics, personal finance strategy, and market dynamics. He specializes in turning complex economic trends into actionable insights for everyday readers.