How can I create Javascript object on the fly in a loop?

Question

I'm looping through an array response and I want to put some values from it into an object data but my method below doesn't work ("data[i] is not defined").

var data = {},
    i = 0;

$(response).each(function(){
    data[i].title = response.title; // This does not work
    data[i].id = response.id;
    i++;
}

I want the resulting object data to look like this:

{
    0: {
          title: "First title",
          id: "First id"
       },

    1: {
          title: "Second title",
          id: "Second id"
       },
}

How can I achieve this?

You need to learn more about the difference between arrays and objects. — givanse
– givanse, Commented Dec 19, 2013 at 14:04

Khanh TO · Accepted Answer · 2013-12-19 14:02:41Z

1

Try:

var data = {},
    i = 0;

$(response).each(function(){
    data[i] = {}; // Initialize an object first before assigning values: data[i] = {};.
    data[i].title = this.title; //Use this instead of response
    data[i].id = this.id;
    i++;
});

answered Dec 19, 2013 at 14:02

Khanh TO

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2 Comments

Weblurk Over a year ago

Thanks, but why use this instead of response? Any differences in the outcome?

Khanh TO Over a year ago

@Weblurk: this is current item in the loop while response is your array

epascarello · Accepted Answer · 2013-12-19 14:07:15Z

1

You are not referencing each index of the response, you are referencing properties off the array/object

$(response).each(function(index){
    data[i].title = response[index].title; 
    data[i].id = response[index].id;
    i++;
});

edited Dec 19, 2013 at 14:07

answered Dec 19, 2013 at 14:01

epascarello

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Comments

hsz · Accepted Answer · 2013-12-19 13:59:36Z

0

Just try with:

var data = [];

$(response).each(function(index, element){
    data.push({
        title: element.title,
        id:    element.id
    });
}

This snippet will create an array with object in it, so you can access them with:

data[0]; // [1], [2] ...

answered Dec 19, 2013 at 13:59

hsz

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1 Comment

Mark Walters Over a year ago

Probably because the structure is not consistent with what the OP asked. Equally response.title doesn't refer to the item in each iteration of the .each() loop

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