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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

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1  
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

2 Answers

up vote 4 down vote accepted

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 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, there are many problems that can arise.

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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
@Anish - Can you be a bit clearer/give an example? The order isn't guaranteed, so backwards/forwards shouldn't be something that you rely on...but an example of what you're after would help in finding a solution. – Nick Craver♦ Nov 27 '10 at 11:54
@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
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up vote 0 down vote

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...

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