How To Fix Jquery Is Not Defined

If you have ever worked with jQuery, you might have encountered the dreaded “jQuery is not defined” error. This error occurs when the browser cannot find the jQuery library, which is required for your jQuery code to function properly. In this blog post, we will discuss various reasons why this error occurs and how to fix it.

Causes of “jQuery is not defined” Error

Here are some common reasons that can lead to the “jQuery is not defined” error:

  • jQuery library is not included in your project or is not loaded properly.
  • Your custom jQuery code is placed before the jQuery library in your HTML file.
  • jQuery library file is corrupt or not compatible with your custom code.
  • Conflict with other JavaScript libraries that use the $ variable.

How to Fix “jQuery is not defined” Error

Follow these steps to resolve the “jQuery is not defined” error:

Step 1: Check If jQuery Is Included and Loaded Properly

First and foremost, make sure that you have included the jQuery library in your project, and it’s being loaded correctly. You can include it either by downloading the jQuery file and linking it in your HTML or by using a CDN (Content Delivery Network) link.

Here’s how you can include jQuery using a CDN link:

    <script src=""></script>

Make sure this script tag is placed inside your HTML’s <head> or at the very end of your <body> tag.

Step 2: Place Your Custom jQuery Code After jQuery Library

Another common mistake is placing your custom jQuery code before the jQuery library. This will result in the browser trying to execute your code before the library is loaded, leading to the “jQuery is not defined” error. To fix this, make sure your custom code follows the jQuery library script tag.


    <script src=""></script>
        $(document).ready(function () {
            // Your custom jQuery code here

Step 3: Check for Compatibility and File Integrity

Make sure that the version of jQuery you’re using is compatible with your custom code. Check the official jQuery website for the latest version and any compatibility notes. Also, ensure that the jQuery file you’re using is not corrupt by downloading it again or using a different CDN link.

Step 4: Resolve Conflicts with Other JavaScript Libraries

jQuery uses the $ variable as an alias for jQuery, and this can cause conflicts with other JavaScript libraries that also use the $ variable. To resolve this issue, you can use the noConflict() method provided by jQuery. This method releases the control of the $ variable, allowing you to use it with other libraries.


        var jq = jQuery.noConflict();
        jq(document).ready(function () {
            // Your custom jQuery code using 'jq' instead of '$'

By following these steps, you should be able to resolve the “jQuery is not defined” error and get your code running smoothly. Happy coding!