[jquery] How to check what version of jQuery is loaded?

How do I check which version of jQuery is loaded on the client machine? The client may have jQuery loaded but I don't know how to check it. If they have it loaded how do I check the version and the prefix such as:

$('.class')
JQuery('.class')

My preference is:

console.debug("jQuery "+ (jQuery ? $().jquery : "NOT") +" loaded")

Result:

jQuery 1.8.0 loaded

// My original 'goto' means to get the version
$.fn.jquery

// Another *similar* option
$().jQuery

// If there is concern that there may be multiple implementations of `$` then:
jQuery.fn.jquery

Recently I have had issues using $.fn.jquery/$().jQuery on a few sites so I wanted to note a third simple command to pull the jQuery version.

If you get back a version number -- usually as a string -- then jQuery is loaded and that is what version you're working with. If not loaded then you should get back undefined or maybe even an error.

Pretty old question and I've seen a few people that have already mentioned my answer in comments. However, I find that sometimes great answers that are left as comments can go unnoticed; especially when there are a lot of comments to an answer you may find yourself digging through piles of them looking for a gem. Hopefully this helps someone out!

You should actually wrap this in a try/catch block for IE:

// Ensure jquery is loaded -- syntaxed for IE compatibility
try
{
    var jqueryIsLoaded=jQuery;
    jQueryIsLoaded=true;
}
catch(err)
{
    var jQueryIsLoaded=false;
}
if(jQueryIsLoaded)
{
    $(function(){
        /** site level jquery code here **/
    });
}
else
{
    // Jquery not loaded
}

…just because this method hasn't been mentioned so far - open the console and type:

$ === jQuery

As @Juhana mentioned above $().jquery will return the version number.

As per Template monster blog, typing, these below scripts will give you the version of the jquery in the site you are traversing now.

 1. console.log(jQuery.fn.jquery);
 2. console.log(jQuery().jquery);

You can just check if the jQuery object exists:

if( typeof jQuery !== 'undefined' ) ... // jQuery loaded

jQuery().jquery has the version number.

As for the prefix, jQuery should always work. If you want to use $ you can wrap your code to a function and pass jQuery to it as the parameter:

(function( $ ) {
    $( '.class' ).doSomething();  // works always
})( jQuery )

In one line and the minimum of keystrokes (oops!):

alert($().jquery);

Go to the developer's Tool > console and write one of the following command jQuery.fn.jquery console.log(jQuery().jquery);

if (jQuery){
   //jquery loaded
}

.....

I have found this to be the shortest and simplest way to check if jQuery is loaded:

if (window.jQuery) {
    // jQuery is available.

    // Print the jQuery version, e.g. "1.0.0":
    console.log(window.jQuery.fn.jquery);
}

This method is used by http://html5boilerplate.com and others.