How to get the keys of an array using javascript?

Question

is there any function to get the keys of an array using javascript

Also i want to reverse and array

eg:

appz_variable['412cc16e']="ABXZ";

appz_variable['axecr6fd']="YCSET";

I want the array indexes or keys in reverse order

Arrays are usually indexed by integers. So what keys are you talking about? Are you talking about hashes? Please provide an example. — Darin Dimitrov, Nov 27 '10 at 11:39
Dupes: http://stackoverflow.com/questions/2980242/js-objects-and-properties, http://stackoverflow.com/questions/3068534/getting-javasctipt-object-key-list, etc — sje397, Nov 27 '10 at 12:01

score 5 · Accepted Answer · edited Oct 23 '14 at 18:35

5

I assume here you're talking about an object which some label (albeit incorrectly) an "associative array". For that situation, use a for...in loop to enumerate the object, like this:

for(var key in myObject) {
  if(myObject.hasOwnProperty(key)) {
    alert("Key: " + key + ", Value: " + myObject[key]);
  }
}

For a normal array you just loop though based on an index, like this:

for(var i=0; i<myArray.length; i++) {
  alert("Position: " + i + ", Value: " + myArray[i]);
}

The second is iterating over the array, while the first is enumerating the object...you shouldn't use a for...in loop on a normal array for example, as there are many problems that can arise.

edited Oct 23 '14 at 18:35

trnelson

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answered Nov 27 '10 at 11:40

Nick Craver

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can u please tell me. how to. reverse an array using the first method – Anish Joseph Nov 27 '10 at 11:51
@Nick Craver - I just updated my question please go through it – Anish Joseph Nov 27 '10 at 11:59
@Anish - Yeah...that order isn't guaranteed, the best you can do is loop through, you can store and presents the results backwards, but **it may very by browser**, so I wouldn't count on the ordering (especially in IE). – Nick Craver Nov 27 '10 at 12:02
I am using php to create that array . So even if I send a reversed array from php it wont be in the same order ??? – Anish Joseph Nov 27 '10 at 12:10
@Anish - nope, not necessarily, as I said this isn't an array, it's an object. – Nick Craver Nov 27 '10 at 12:11

score -1 · Answer 2 · answered Nov 27 '10 at 14:02

-1

You can index your array by numbers when it is created. perhaps like this:

appz_variable[0]['412cc16e']="ABXZ";
appz_variable[1]['axecr6fd']="YCSET";

and then you will have an "order" which you can then reverse...

answered Nov 27 '10 at 14:02

Yuval A.

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How to get the keys of an array using javascript?

2 Answers2