is there an equalant to PHP array_key_exists in javascript or jquery

Question

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?

http://stackoverflow.com/questions/1098040/checking-if-an-associative-array-key-exists-in-javascript seems to give you a couple of options — JoshuaWohle, Aug 02 '12 at 11:02
Please refer to this post. http://stackoverflow.com/questions/1098040/checking-if-an-associative-array-key-exists-in-javascript — Vins, Aug 02 '12 at 11:02
This question is also about numeric array, so, not JSON object. — Peter Krauss, Aug 13 '16 at 23:55

Flash · Accepted Answer · 2012-08-02T11:15:06.540

16

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.

edited Aug 02 '12 at 11:15

answered Aug 02 '12 at 11:01

Flash

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The question is bout traditional arrays also, it work for Array()? – Peter Krauss Aug 13 '16 at 23:52

score 6 · Answer 2 · answered Aug 02 '12 at 11:03

6

In Javascript....

if(nameofarray['preferenceIDTmp'] != undefined) {
    // It exists
} else {
    // Does not exist
}

answered Aug 02 '12 at 11:03

Brian

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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 02 '12 at 11:06

score 2 · Answer 3 · answered Aug 02 '12 at 11:01

2

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

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

answered Aug 02 '12 at 11:01

Pete

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is there an equalant to PHP array_key_exists in javascript or jquery

3 Answers3