CODEWITHSUNDEEP
javascript
Wracker
Wracker

Reputation: 619

javascript shuffling object properties with their values

Hello everyone,

what I'd like to achieve is to shuffle all the object's properties including their values...

object:

    var numbers = { one : 1, two : 2, three : 3};

result: 

     Object {two: 2, one: 1, three: 3}

or any other variation

I have tried couple of array shuffle methods but none of them worked for me...

Upvotes: 2

Views: 4744

Answers (2)

T.J. Crowder
T.J. Crowder

Reputation: 1075309

As of ECMAScript 2015 (ES2015, aka ES6), object properties do have an order (they didn't before):

  1. Let keys be a new empty List.
  2. For each own property key P of O that is an integer index, in ascending numeric index order
    • Add P as the last element of keys.
  3. For each own property key P of O that is a String but is not an integer index, in property creation order
    • Add P as the last element of keys.
  4. For each own property key P of O that is a Symbol, in property creation order
    • Add P as the last element of keys.
  5. Return keys.

Consequently, it's now possible to do what you asked, by creating a new object and adding the properties to it in the order you want them to appear:

let numbers = { one : 1, two : 2, three : 3};
numbers = Object.keys(numbers)
    .map((key) => ({key, value: numbers[key]}))
    .sort((a, b) => b.key.localeCompare(a.key))
    .reduce((acc, e) => {
      acc[e.key] = e.value;
      return acc;
    }, {});
console.log(JSON.stringify(numbers));

Live Example

That's sorted, not shuffled, but instead of sort you can shuffle in any of several ways, as outlined in this question's answers.

That works on ES2015+ JavaScript engines. I'm not saying it (using property order this way) a worthwhile thing to do. :-)

You could argue that that's a bit of an abusage of reduce, but it let me keep it all to one big expression. (Which you could further argue is a silly thing for me to do. :-) )

Upvotes: 6

Niet the Dark Absol
Niet the Dark Absol

Reputation: 324780

Objects are unordered. Some browsers may sort their keys alphabetically, but this is outside of any specification as the spec says unordered.

But what you can do is this:

var keys = Object.keys(numbers);
// drop your preffered shuffle algorithm here
keys.sort(function(a,b) {return Math.random() - 0.5;});
// now you have random keys!

keys.forEach(function(k) {console.log(numbers[k]);});

Upvotes: 3

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