How do I check whether jQuery is loaded in the page or not? I have to run a jQuery script which has a jQuery library link, but when I use the code I want to make sure to load that file only if the page does not have any jQuery file, otherwise use that file. Any suggestions?

How do I check whether jQuery is loaded in the page or not? I have to run a jQuery script which has a jQuery library link, but when I use the code I want to make sure to load that file only if the page does not have any jQuery file, otherwise use that file. Any suggestions?

• javascript
• jquery

Share Improve this question Follow edited Dec 21, 2011 at 19:32 Adam 45k1717 gold badges107107 silver badges145145 bronze badges asked Dec 21, 2011 at 19:27 disckydiscky 15.3k88 gold badges2222 silver badges1111 bronze badges

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4 Answers 4

Sorted by: Reset to default 7

if (typeof jQuery == 'undefined') {
   // This means jQuery is not loaded
}

Also, take a look at yepnope.js, it allows you to load different JavaScript files based on if certain conditions are true or false.

if (typeof jQuery != 'undefined') {
 // jQuery is loaded
}

The simplest:

if( window.jQuery ) { 

 // you code here 
} 

To check if jQuery is loaded on the page try:

if (!(window.jQuery || window.$)){
 //then load it
} else {
//already loaded
}