Push Object in Array [duplicate]

Question

 var p = {
     id: null
 };
 for (var copyArray = [], i = 0; i < 3; i++) {
     copyArray.push(p);
     copyArray[i].id = (copyArray.length) - parseInt(1, 10);
 }
 console.log(copyArray);

All id in copyArray is getting 2 value. Result CopyArray({id=2},{id=2},{id=2})

Doing normal push operation of object in array, and updating the index after insertion.

But somehow all id's in the copy array are getting same id What wrong i am doing over here

Side note: parseInt(1, 10) is just a long-winded and inefficient way to write 1. parseInt is for parsing strings as integers. — T.J. Crowder
– T.J. Crowder, Commented Aug 24, 2015 at 6:06
@Alex Converting to Decimal, you can also use 2, 8, 16 for binary, octal, hex respectively — Tushar
– Tushar, Commented Aug 24, 2015 at 6:07
@Alex: The radix (number base) to use. 10 (decimal) is the number base we normally write numbers in. It's 10 because each "place" in a number is a power of 10. E.g., 123 is (1 x 10²) + (2 x 10¹) + (3 x 10⁰). — T.J. Crowder
– T.J. Crowder, Commented Aug 24, 2015 at 6:07
@Alex: I didn't use any one resource, just a lot of things I've picked up over the years. My two primary references are the specification and MDN. MDN is more user-friendly, but is also collaboratively-edited by anyone who wants to sign up for a Mozilla account. It used to be consistently excellent; the last couple of years people have been contributing who aren't quite as rigorous and well-informed as the original authors, Still very good. Do not use w3schools. — T.J. Crowder
– T.J. Crowder, Commented Aug 24, 2015 at 6:15

T.J. Crowder · Accepted Answer · 2015-08-24 06:03:45Z

9

You're pushing the same object into the array repeatedly, and just updating the id property on that object as you go.

If you want multiple objects in the array, you'll need to create multiple objects:

var copyArray = [];
while (copyArray.length < 3) {
  copyArray.push({
    id: copyArray.length
  });
}
snippet.log(JSON.stringify(copyArray));

<!-- Script provides the `snippet` object, see http://meta.stackexchange.com/a/242144/134069 -->
<script src="http://tjcrowder.github.io/simple-snippets-console/snippet.js"></script>

answered Aug 24, 2015 at 6:03

T.J. Crowder

1.1m201 gold badges2k silver badges2k bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Kunal Vashist Over a year ago

It worked thanks.. Is there any explanation why we can't do that way,,?

T.J. Crowder Over a year ago

@KunalVashist: The first sentence is the explanation: You're pushing the same object repeatedly.

Ziki · Accepted Answer · 2015-08-24 06:27:56Z

-1

You can also create a function that will create clone for the Object:

JSON.clone = function(json) {
    var
        temp = null,
        key = null;

    if (json === null || typeof json !== 'object') {
        return json;
    }
    temp = json.constructor(); // changed
    for (key in json) {
        if (json.hasOwnProperty(key)) {
            temp[key] = JSON.clone(json[key]);
        }
    }
    return temp;
};

Then you can use your original code but with little changes:

var p = {
    id: null
};
for (var copyArray = [], i = 0; i < 3; i++) {
    copyArray.push(JSON.clone(p));
    copyArray[i].id = copyArray.length - 1;
}
console.log(copyArray);

answered Aug 24, 2015 at 6:27

Ziki

1,4412 gold badges14 silver badges34 bronze badges

1 Comment

Ziki Over a year ago

why down-vote this answer?

Collectives™ on Stack Overflow

Push Object in Array [duplicate]

2 Answers 2

2 Comments

1 Comment

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

1 Comment

Linked

Related