Turning an array into an array of objects

Question

How do I turn this array with keys

> dd
[ 'DeviceName',
  'counter1',
  'counter2',
  'counter3',
  'counter4' ]

into this object array with objects

[
    { data: 'DeviceName' },
    { data: 'counter1' },
    { data: 'counter2' },
    { data: 'counter3' },
    { data: 'counter4' }
]

I have tried this function, but the problem is that the data key is the same in them all.

Is there a way around this?

 newdd=function toObject(arr) {
      var rv = {};
      var a =[];
        for (var i = 0; i < arr.length; ++i) {
        rv["data"] = arr[i];
        a.push(rv);
        }
      return a;
    }

This gives me:

> newdd(dd)
[ { data: 'counter4' },
  { data: 'counter4' },
  { data: 'counter4' },
  { data: 'counter4' },
  { data: 'counter4' } ]

think [this](http://stackoverflow.com/questions/22280580/turning-an-array-into-an-array-of-objects-with-underscore-js) might be what I want — HattrickNZ, Sep 03 '15 at 00:14

score 5 · Accepted Answer · answered Sep 03 '15 at 00:18

5

Array.prototype.map():

dd.map(function(element)
{
    return { data: element };
});

answered Sep 03 '15 at 00:18

Siguza

21,155
6
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score 4 · Answer 2 · edited May 23 '17 at 12:30

That's because objects in JavaScript are passed by reference (or really call by sharing), not by value, so you're always referencing the same object.

Just move your assignment for rv = {} inside your for loop and it should fix your problem. Reassigning rv to a new object as opposed to modifying the existing instance will result in the desired behavior.

newdd = function toObject(arr) {
    var a =[];
    for (var i = 0; i < arr.length; ++i) {
        var rv = {};
        rv["data"] = arr[i];
        a.push(rv);
    }

    return a;
 }

See Working with objects on the Mozilla Developer Network to help build your understanding of objects.

Andy · Answer 3 · 2015-11-16T16:58:16.340

2

Try this instead:

function toObject(arr) {
    var a =[];
    for (var i = 0; i < arr.length; ++i) {
        a.push({ data: arr[i] });
    }
    return a;
}

edited Nov 16 '15 at 16:58

answered Sep 03 '15 at 00:17

Andy

61,948
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Turning an array into an array of objects

3 Answers3