JQuery - $ is not defined

That error can only be caused by one of three things:

Your JavaScript file is not being properly loaded into your page You have a botched version of jQuery. This could happen because someone edited the core file, or a plugin may have overwritten the $ variable. You have JavaScript running before the page is fully loaded, and as such, before jQuery is fully loaded.

First of all, ensure, what script is call properly, it should looks like

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js" type="text/javascript"></script>

and shouldn't have attributes async or defer.

Then you should check the Firebug net panel to see if the file is actually being loaded properly. If not, it will be highlighted red and will say "404" beside it. If the file is loading properly, that means that the issue is number 2.

Make sure all jQuery javascript code is being run inside a code block such as:

$(document).ready(function () {
  //your code here
});

This will ensure that your code is being loaded after jQuery has been initialized.

One final thing to check is to make sure that you are not loading any plugins before you load jQuery. Plugins extend the "$" object, so if you load a plugin before loading jQuery core, then you'll get the error you described.

Note: If you're loading code which does not require jQuery to run it does not need to be placed inside the jQuery ready handler. That code may be separated using document.readyState.

---

It could be that you have your script tag called before the jquery script is called.

<script type="text/javascript" src="js/script.js"></script>

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js" type="text/javascript"></script>

This results as $ is not defined

Put the jquery.js before your script tag and it will work ;) like so:

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js" type="text/javascript"></script>

<script type="text/javascript" src="js/script.js"></script>

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First you need to make sure that jQuery script is loaded. This could be from a CDN or local on your website. If you don't load this first before trying to use jQuery it will tell you that jQuery is not defined.

<script src="jquery.min.js"></script>

This could be in the HEAD or in the footer of the page, just make sure you load it before you try to call any other jQuery stuff.

Then you need to use one of the two solutions below

(function($){
// your standard jquery code goes here with $ prefix
// best used inside a page with inline code, 
// or outside the document ready, enter code here
 })(jQuery); 

or

jQuery(document).ready(function($){
// standard on load code goes here with $ prefix
// note: the $ is setup inside the anonymous function of the ready command
});

please be aware that many times $(document).ready(function(){//code here}); will not work.

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If the jQuery plugin call is next to the </body>, and your script is loaded before that, you should make your code run after window.onload event, like this:

window.onload = function() {
  //YOUR JQUERY CODE
}

`

so, your code will run only after the window load, when all assets have been loaded. In that point, the jQuery ($) will be defined.

If you use that:

$(document).ready(function () {
  //YOUR JQUERY CODE
});

`

the $ isn't yet defined at this time, because it is called before the jQuery is loaded, and your script will fail on that first line on console.

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I just did the same thing and found i had a whole lot of

type="text/javacsript"

So they were loading, but no further hint as to why it wasn't working. Needless to say, proper spelling fixed it.

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Use a scripts section in the view and master layout.

Put all your scripts defined in your view inside a Scripts section of the view. This way you can have the master layout load this after all other scripts have been loaded. This is the default setup when starting a new MVC5 web project. Not sure about earlier versions.

Views/Foo/MyView.cshtml:

// The rest of your view code above here.

@section Scripts 
{ 
    // Either render the bundle defined with same name in BundleConfig.cs...
    @Scripts.Render("~/bundles/myCustomBundle")

    // ...or hard code the HTML.
    <script src="URL-TO-CUSTOM-JS-FILE"></script>

    <script type="text/javascript">
      $(document).ready(function () {

        // Do your custom javascript for this view here. Will be run after 
        // loading all the other scripts.            
      });
    </script>
}

Views/Shared/_Layout.cshtml

<html>
<body>
    <!-- ... Rest of your layout file here ... -->

    @Scripts.Render("~/bundles/jquery")
    @Scripts.Render("~/bundles/bootstrap")
    @RenderSection("scripts", required: false)
</body>
</html>

Note how the scripts section is rendered last in the master layout file.

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It means that your jQuery library has not been loaded yet.

You can move your code after pulling jQuery library.

or you can use something like this

window.onload = function(){
  // Your code here
  // $(".some-class").html("some html");
};  

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As stated above, it happens due to the conflict of $ variable.

I resolved this issue by reserving a secondary variable for jQuery with no conflict.

var $j = jQuery.noConflict();

and then use it anywhere

$j( "div" ).hide();

more details can be found here

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make sure you really load jquery this is not jquery - it's the ui!

  <script language="JavaScript" 
    src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.10.0/jquery-ui.min.js">
  </script>

This is a correct script source for jquery:

 <script language="JavaScript"  src="http://ajax.googleapis.com/ajax/libs/jquery/1.10.0/jquery.min.js"></script>

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Are you using any other JavaScript libraries? If so, you will probably need to use jQuery in compatibility mode:

http://docs.jquery.com/Using_jQuery_with_Other_Libraries

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after some tests i found a fast solution , you can add in top of your index page:

<script>
$=jQuery;
</script>

it work very fine :)

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I had the same problem and resolved it by using

document.addEventListener('DOMContentLoaded', () => {
 // code here
});

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I got the same error message when I misspelled the jQuery reference and instead of type="text/javascript" I typed "...javascirpt". ;)

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It sounds like jQuery isn't loading properly. Which source/version are you using?

Alternatively, it could a be namespace collision, so try using jQuery explicitly instead of using $. If that works, you may like to use noConflict to ensure the other code that's using $ doesn't break.

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That error means that jQuery has not yet loaded on the page. Using $(document).ready(...) or any variant thereof will do no good, as $ is the jQuery function.

Using window.onload should work here. Note that only one function can be assigned to window.onload. To avoid losing the original onload logic, you can decorate the original function like so:

originalOnload = window.onload;
window.onload = function() {
  if (originalOnload) {
    originalOnload();
  }
  // YOUR JQUERY
};

This will execute the function that was originally assigned to window.onload, and then will execute // YOUR JQUERY.

See https://en.wikipedia.org/wiki/Decorator_pattern for more detail about the decorator pattern.

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I use Url.Content and never have a problem.

<script src="<%= Url.Content ("~/Scripts/jquery-1.4.1.min.js") %>" type="text/javascript"></script>

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In the solution it is mentioned - "One final thing to check is to make sure that you are not loading any plugins before you load jQuery. Plugins extend the "$" object, so if you load a plugin before loading jQuery core, then you'll get the error you described."

For avoiding this -

Many JavaScript libraries use $ as a function or variable name, just as jQuery does. In jQuery's case, $ is just an alias for jQuery, so all functionality is available without using $. If we need to use another JavaScript library alongside jQuery, we can return control of $ back to the other library with a call to $.noConflict():

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I had this problem once for no apparent reason. It was happenning locally whilst I was running through the aspnet development server. It had been working and I reverted everything to a state where it had previously been working and still it didn't work. I looked in the chrome debugger and the jquery-1.7.1.min.js had loaded without any problems. It was all very confusing. I still don't know what the problem was but closing the browser, closing the development server and then trying again sorted it out.

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Just place jquery url on the top of your jquery code

like this--

<script src="<%=ResolveUrl("~/Scripts/jquery-1.3.2.js")%>" type="text/javascript"></script>

<script type="text/javascript">
    $(function() {
        $('#post').click(function() {
            alert("test"); 
        });
    });
</script>

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I had the same problem and it was because my reference to the jQuery.js was not in the tag. Once I switched that, everything started working.

Anthony

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Check the exact path of your jquery file is included.

if you add this on bottom of your page , please all call JS function below this declaration.

Check using this code test ,