Fixing the "Uncaught ReferenceError: $ is not defined" Error in jQuery

Fixing the "Uncaught ReferenceError: $ is not defined" Error in jQuery

The "Uncaught ReferenceError: $ is not defined" error is a common issue that web developers encounter when working with jQuery. This error occurs when the jQuery library is not loaded properly, or when there is a conflict with another library using the `$` symbol. In this article, we'll explore the possible causes of this error and provide solutions to fix it.

1. Ensure jQuery is Loaded Correctly

The most common cause of the "Uncaught ReferenceError: $ is not defined" error is that jQuery is not loaded correctly or is missing from your project. To fix this issue, make sure that the jQuery library is included in your HTML file before your custom JavaScript code:

  1. <!DOCTYPE html>
  2. <html>
  3. <head>
  4. <script src="https://code.jquery.com/jquery-3.6.0.min.js"></script>
  5. </head>
  6. <body>
  7. <!-- Your HTML content -->
  8.  
  9. <script src="your-custom-script.js"></script>
  10. </body>
  11. </html>

In this example, the jQuery library is loaded from the official CDN before the custom script, ensuring that `$` is defined when your custom script is executed.

2. Check for jQuery Version Compatibility

Another potential cause of the error is using a version of jQuery that is not compatible with your code. To fix this, check your code for any deprecated features or syntax, and ensure that you are using a compatible version of jQuery. You can refer to the official jQuery migration guide for help with updating your code to work with newer versions of jQuery.

3. Resolve Conflicts with Other Libraries

Sometimes, the "Uncaught ReferenceError: $ is not defined" error occurs when another JavaScript library is using the `$` symbol, causing a conflict with jQuery. To resolve this issue, you can use jQuery's `noConflict()` method:

  1. const j = jQuery.noConflict();
  2.  
  3. j(document).ready(function() {
  4. j('selector').click(function() {
  5. // Your jQuery code
  6. });
  7. });

In this example, the `noConflict()` method releases the `$` symbol, allowing you to assign it to another variable (in this case, `j`). You can then use this variable as a substitute for `$` in your jQuery code.

4. Verify the Order of Script Loading

In some cases, the error may be caused by the order in which scripts are loaded. Make sure that your custom JavaScript code is placed after the jQuery library in your HTML file. Loading your script before jQuery can lead to the "Uncaught ReferenceError: $ is not defined" error:

  1. <!DOCTYPE html>
  2. <html>
  3. <head>
  4. <script src="https://code.jquery.com/jquery-3.6.0.min.js"></script>
  5. <script src="your-custom-script.js"></script>
  6. </head>
  7. <body>
  8. <!-- Your HTML content -->
  9. </body>
  10. </html>

By ensuring the correct order of script loading, you can avoid encountering the error due to improper script execution order.


In conclusion, the "Uncaught ReferenceError: $ is not defined" error in jQuery can be resolved by ensuring that jQuery is loaded correctly, checking for version compatibility, resolving conflicts with other libraries, and verifying the order of script loading. By addressing these potential issues, you can ensure that your jQuery code runs smoothly and as intended, providing a seamless experience for your users.

Remember to refer to the official jQuery documentation for further information and details about jQuery's features and usage. By understanding the common causes of the "Uncaught ReferenceError: $ is not defined" error and knowing how to resolve them, you'll be better equipped to handle issues that arise during your web development journey.

Keep these solutions in mind, and you'll be well on your way to writing more robust and error-free jQuery code. Happy coding!

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