Question

70

Is there a difference in Initializing javascript variable using [] versus {}

rated 0 times [ 76] [ 6] / answers: 1 / hits: 16107 / 11 Years ago, tue, june 4, 2013, 12:00:00

Well I have always used

var j= {};

j['field'] = value;

Apparently below works too

var j= [];

j['field'] = value;

Any difference?

Edit: Sorry I guess I used the wrong word json here instead of object. My bad. But my questions till stands. Most people are explaining the difference between an array and object to me which I am familiar with.

I always do var x = []; x.push('blah') etc.

I also do var x = {}; x.Name = 'Michael'; x.Age = 21 etc.

What I was surprised to see and what prompted me to ask this is I saw code that goes like
var x = [];
x.name = 'Michael';

This is something I wasn't used to and hence posted the question.

Thanks for all the answers. I have marked accepted answer which addressed my question the best

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rhett

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3 Years ago

answered 11 Years ago cristinadomoniquel · Accepted Answer

Your objects aren't JSON, they're (empty) object and array literals. JSON is the serialized form you get by passing such a value of JSON.stringify.

The latter won't work if you do try to convert it to JSON, even though it's legal JavaScript:

var json = [];             // ok, it's an array

json[field] = value;   // still OK - arrays can have properties too

JSON.stringify(json);

> []

i.e. you just get an empty array, because when you try to serialize an array you only get out the numerically indexed properties from 0 to myArray.length - 1, and not named properties.