Javascript array

Question

Im am working with some code from another developer and came across something I have not seen before. The basic functionality of the code is to look for a piece of data in an object within an object. The object format is theObj {key:Object, key:Object,...}, the data being searched for is stored in 2 variables inkey,lookfor.

$.each(theObj, function(m,n){
    if(typeof(n['data'][inkey]) != "undefined" && n['data'][inkey] !== null) {
        if(n['data'][inkey][lookfor] == 1){..}
    }
});

What does the ['data'] do?

It is the key in the object. Meaning n['data'] means get `value of key(propery name) data in object n`. — Selvakumar Arumugam, Jun 03 '13 at 14:35
It's called **bracket notation**. It access the property `data` or the object `n`. You already know this from arrays: `arr[0]` accesses the first element of the array, the property `0` of the array `arr`. — Felix Kling, Jun 03 '13 at 14:36

score 4 · Answer 1 · answered Jun 03 '13 at 14:36

4

It is looking for a property data in the object n - n['data'] is the same as n.data

answered Jun 03 '13 at 14:36

karthikr

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score 2 · Accepted Answer · answered Jun 03 '13 at 14:40

n['data'] is the same as n.data but sometime it's useful to use brackets like when you need to use a variable like n['data'][inkey].

Btw you or him should use n.data.hasOwnProperty(inkey) instead of typeof(n['data'][inkey]) != "undefined"

You could write it like that :

$.each(theObj, function(m,n){
    if(n.data.hasOwnProperty(inkey) && n.data[inkey] !== null) {
        if(n.data[inkey][lookfor] == 1){..}
    }
});

Selvakumar Arumugam · Answer 3 · 2013-06-03T14:48:23.070

1

data is the property name or key in the object. So n['data'] would return the property value for the property name data in object n.

And what you have is an Object not an Array.

Array contains list of elements with integer based index, where else Object contains list of elements with key based index.

edited Jun 03 '13 at 14:48

answered Jun 03 '13 at 14:37

Selvakumar Arumugam

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Javascript array

3 Answers3