How to shuffle an array of objects in javascript?

Question

The code below works for a normal array but not with an array with object does anybody knows how to do this?

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Answer 1

If you need to shuffle a collection of element nodes (in the DOM), convert it to an array first:

var wrapper = document.getElementById('someid');
var array = Array.prototype.slice.call(wrapper.children);

Shuffling a HTMLCollection object (as returned by children) directly doesn't work even if you can iterate the collection with a for loop. This stumbled me for a while.

Answer 2

Try sorting like this snippet:

console.log( [
    { some: 1 },
    { some: 2 },
    { some: 3 },
    { some: 4 },
    { some: 5 },
    { some: 6 },
    { some: 7 },
  ]
  .sort( () => Math.random() - 0.5) );

In reponse to Martin Omanders comment: here's a shuffle method according to the Fisher-Yates algorithm

for (let i=0; i<20; i+=1) {
  console.log(JSON.stringify(shuffleFisherYates([0,1,2,3,4,5,6,7,8,9])));
}

function shuffleFisherYates(array) {
  let i = array.length;
  while (i--) {
    const ri = Math.floor(Math.random() * (i + 1));
    [array[i], array[ri]] = [array[ri], array[i]];
  }
  return array;
}

Which may be condensed to a one liner (note: this one liner will not compile in the Google Closure Compiler with level advanced):

const shuffle = array => 
  [...Array(array.length)]
    .map((...args) => Math.floor(Math.random() * (args[1] + 1)))
    .reduce( (a, rv, i) => ([a[i], a[rv]] = [a[rv], a[i]]) && a, array);
    
for (let i=0; i<100; i+=1)
  console.log(JSON.stringify(shuffle([0,1,2,3,4,5,6,7,8,9])));

Answer 3

Here is one more example based on lodash _.shuffle.

const array = [
    { some: 1 },
    { some: 2 },
    { some: 3 },
    { some: 4 },
    { some: 5 },
    { some: 6 },
    { some: 7 },
  ];
console.log(_.shuffle(array));

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.js"></script>