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up vote 2 down vote favorite

Possible Duplicate:
Checking if an associative array key exists in Javascript

i have a PHP code block . for a purpose i am converting this to a javascript block ,

i have PHP

if(array_key_exists($val['preferenceIDTmp'], $selected_pref_array[1]))

now i want to do this in jquery . is there any built in function to do this , i am stuck , please help , thanks in advance .

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marked as duplicate by deceze, watcher, j0k, Hamish, GDP Aug 3 '12 at 0:48

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.
    
stackoverflow.com/questions/1098040/… seems to give you a couple of options –  JoshuaWohle Aug 2 '12 at 11:02
    
Please refer to this post. stackoverflow.com/questions/1098040/… –  Vins Aug 2 '12 at 11:02

3 Answers 3

up vote 3 down vote

Note that objects (with named properties) and associative arrays are the same thing in javascript.

You can use hasOwnProperty to check if an object contains a given property:

o = new Object();  
o.prop = 'exists'; // or o['prop'] = 'exists', this is equivalent 

function changeO() {  
  o.newprop = o.prop;  
  delete o.prop;  
}  

o.hasOwnProperty('prop');   //returns true  
changeO();  
o.hasOwnProperty('prop');   //returns false

Alternatively, you can use:

if (prop in object)

The subtle difference is that the latter checks the prototype chain.

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up vote 1 down vote

In Javascript....

if(nameofarray['preferenceIDTmp'] != undefined) {
    // It exists
} else {
    // Does not exist
}
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You want to check for undefined with === or !== otherwise you'll get false positives for null and false. –  Sam Peacey Aug 2 '12 at 11:06
up vote 2 down vote

http://phpjs.org/functions/array_key_exists:323

This is a great site for PHP programmers moving to js.

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