Get array count in Javascript

Question

I have an array like this:

elements = {
    opinions: ['p31/php/endpoint.php?get=opinions'], // function to call and API endpoint, php/endpoint.php
    top3positive: ['p31/php/endpoint.php?get=top3positive'], // function to call andAPI endpoint, php/endpoint.php
    top3negative: ['p31/php/endpoint.php?get=top3negative'], // function to call andAPI endpoint, php/endpoint.php
};

How do I point to the 1 first array. If I do alert(elements[0]); it is not returning opinions as I would expect. What am I doing wrong?

I need to point to the array index based on its order 0,1,2 etc.

Thanks

The `{}` notation is for objects, not arrays. You access `opinions` by doing `elements.opinions`. — whatyouhide, Nov 06 '13 at 22:49
@whatyouhide What if I need to access the index by number? How do I convert it in an array? — , Nov 06 '13 at 22:51
I posted an answer which explains the object/array confusion here. — whatyouhide, Nov 06 '13 at 22:53
This w3school webpage shows lots of examples of using arrays in javascript: http://www.w3schools.com/js/js_obj_array.asp — Andrew - OpenGeoCode, Nov 06 '13 at 22:53
http://stackoverflow.com/questions/3865139/cast-javascript-object-to-array-how-to — Brenden, Nov 06 '13 at 22:58

score 3 · Answer 1 · answered Nov 06 '13 at 22:52

3

The {} notation creates objects, not arrays. Hence, they are not integer-indexed and their properties have to be accessed using a classic dot notation or using [].

If you want an array, this is the correct way to build it:

elements = [
    'p31/php/endpoint.php?get=opinions', // function to call and API endpoint, php/endpoint.php
    'p31/php/endpoint.php?get=top3positive', // function to call andAPI endpoint, php/endpoint.php
    'p31/php/endpoint.php?get=top3negative', // function to call andAPI endpoint, php/endpoint.php
];

If you leave your object as is in your question, you can access e.g. its first element like this:

elements.opinions;

or

elements['opinions'];

Micro-edit

I left a trailing comma in the array, which is fine in modern browsers but can cause some issues in older IEs. Just to be clear :)

answered Nov 06 '13 at 22:52

whatyouhide

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Array don't have keys in JS. I mean you can add them, but that's abusing the data structure. (resolved) – fncomp Nov 06 '13 at 22:53
OOOPS sorry sorry sorry, I forgot to remove them :) – whatyouhide Nov 06 '13 at 22:53
Happens, just wanted to clarify :) – fncomp Nov 06 '13 at 22:55
he needs to know how to convert the object to an array, not access the object like and array – Brenden Nov 06 '13 at 23:00
@Brenden objects are not ordered collections, so he can't convert it into an array and be sure to access `opinions` when accessing `elements[0]`. – whatyouhide Nov 06 '13 at 23:02

Caner Akdeniz · Answer 2 · 2013-11-06T22:57:15.637

0

Since you set them as objects, you can access them as:

elements['opinions'];
elements['top3positive'];
elements['top3negative'];

If you want to set them as an array then:

var elements=['p31/php/endpoint.php?get=opinions','p31/php/endpoint.php?get=top3positive','p31/php/endpoint.php?get=top3negative'];

Then when you want to access to the item in array you can do:

elements[0];

edited Nov 06 '13 at 22:57

answered Nov 06 '13 at 22:51

Caner Akdeniz

1,862
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Yes I understand this, but as I said I need to access them by index with a number. How do I convert this object into an array – Nov 06 '13 at 22:52

Get array count in Javascript

2 Answers2

Micro-edit