JS Object structuring and addition

Question

Just a question about JS object structuring. I have an object called mainObject I want to push values in so they appear in a format like the second section of code. The values will be added in a loop. I want to be able to do something along the lines of:-

mainObject.data.push({lat : val['lat'], lng: val['lng'], count: 40});}

Could someone tell me how I can go about doing this? Trying to get my head around JS objects.

var mainObject = {
    max: 46};

var mainObject = {
            max: 46,
            data: [{lat: 33.5363, lng:-117.044, count: 1},{lat: 33.5608, lng:-117.24, count: 1},{lat: 38, lng:-97, count: 1},{lat: 38.9358, lng:-77.1621, count: 1}]
    };

Thanks :)

It depends. Where are the values coming from? Array? Object? — Elliot Bonneville
– Elliot Bonneville, Commented Mar 12, 2013 at 15:57
Why do you have var mainObject twice? With the second one, your push code should work well — Bergi
– Bergi, Commented Mar 12, 2013 at 16:05

Ryan · Accepted Answer · 2013-03-12 16:01:30Z

2

In javascript .push is reserved for arrays. To add to an object that already has a property you can simply do this.

var mainObject = {
    max: 46
};

mainObject.data = [{lat : val['lat'], lng: val['lng'], count: 40}];

You would then end up with an object that looked like this:

mainObject{
    max : 46,
    data : [{lat : val['lat'], lng: val['lng'], count: 40}]
}

Which is what you wanted.

EDIT:

@cristoph pointed out that if you change the instansiation of your initial mainObject then you could do this:

 var mainObject = {
     max : 46,
     data : [] 
 }

 mainObject.data.push({lat : val['lat'], lng: val['lng'], count: 40});

Which would give you the same result.

Either way you choose to do it, once data is a property of mainObject and is an array, you can then continue to use .push to insert more elements into it.

So doing this to the above:

 mainObject.data.push({foo : bar});

Would yield:

 mainObject{
     max : 46,
     data : [{lat : val['lat'], lng: val['lng'], count: 40}, {foo : bar}]
 }

edited Mar 12, 2013 at 16:01

answered Mar 12, 2013 at 15:55

Ryan

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4 Comments

Christoph Over a year ago

push is perfectly fine if he has mainObject{max:46,data:[]}. So probably the only thing OP needs to change is the initialisation of the mainObject.

Ryan Over a year ago

@Christoph yes if he already has the data property and it's value is an array. I believe that he wanted to add a new property, which you would do with the code that I presented

user1840255 Over a year ago

But what if I'm pushing multiple items?

Ryan Over a year ago

@user1840255 see my newest update, that should answer all your questions.

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