javascript - jquery return value of a non-existing id or class? - Stack Overflow

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I need to check if an object has same id on DOM, because i am trying to create a modal window library,

the problem is in browsers console when i write

$("#anonexistingid");

it returns []

but in my code

if($("#"+id)!==[]){
        return;
    }

just does not work. What is the proper way of defining an empty array?(Because i think [] means empty array, maybe not i am not sure :D)

I need to check if an object has same id on DOM, because i am trying to create a modal window library,

the problem is in browsers console when i write

$("#anonexistingid");

it returns []

but in my code

if($("#"+id)!==[]){
        return;
    }

just does not work. What is the proper way of defining an empty array?(Because i think [] means empty array, maybe not i am not sure :D)

• javascript
• jquery

Share Improve this question Follow edited Jul 2, 2011 at 19:44 user113716 323k6464 gold badges453453 silver badges441441 bronze badges asked Jul 2, 2011 at 19:38 gkaykckgkaykck 2,3671111 gold badges3535 silver badges5252 bronze badges 1

• 1 In any case, two objects are only equal if they are identical (the same). Even [] == [] returns false. – Felix Kling Commented Jul 2, 2011 at 19:45

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4 Answers 4

Sorted by: Reset to default 9

JQuery always returns an object. you can check it's length to see if it's empty or not:

if($("#"+id).length !== 0){

}

[] is an empty array. To test if empty, try:

if($("#"+id).length) { 
     //Element is found
}

try this . it returns true if object is empty , else returns false

 jQuery.isEmptyObject({}) // true
 jQuery.isEmptyObject({ foo: "bar" }) // false

http://api.jquery./jQuery.isEmptyObject/

You could use the size() method.

   if($("#"+id).size() > 0){
        return;
    }

This method returns the number of matched elements by $.

Hope this helps. Cheers

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