How To Know If Jquery Is Loaded

by

jQuery is a popular and widely-used JavaScript library that simplifies various tasks such as HTML document traversal, event handling, and animations. It’s essential to ensure that jQuery is loaded correctly on your webpage before executing any jQuery code. In this blog post, we’ll discuss different ways to check if jQuery is loaded on your webpage.

1. Use the Browser Console

The easiest way to check if jQuery is loaded is by using the browser console. To do this, follow these steps:

  1. Open your webpage in the browser.
  2. Open the browser’s Developer Tools using one of the following methods:
    • Right-click on the webpage and select “Inspect” or “Inspect Element.”
    • Press Ctrl+Shift+I (Windows/Linux) or Cmd+Opt+I (Mac) on your keyboard.
  3. Click on the “Console” tab in the Developer Tools window.
  4. Type jQuery or $ in the console and press Enter. If jQuery is loaded, it will display the jQuery object with its version number. If not, it will display an undefined error.

2. Check in JavaScript Code

You can also check if jQuery is loaded within your JavaScript code. To do this, you can use the following if statement:

    if (typeof jQuery === 'undefined') {
        console.log('jQuery is not loaded');
    } else {
        console.log('jQuery is loaded, version: ' + jQuery.fn.jquery);
    }

This code checks if the jQuery object is defined. If it’s not defined (i.e., jQuery is not loaded), it will log ‘jQuery is not loaded’ in the console. If jQuery is loaded, it will log ‘jQuery is loaded, version: [version number]’ in the console.

3. Use a Fallback

It’s a good idea to have a fallback option in case the jQuery library fails to load from the specified source. You can use the following code to load jQuery from a local file if it fails to load from the CDN:

    <script src="https://code.jquery.com/jquery-3.6.0.min.js"></script>
    <script>
        if (typeof jQuery === 'undefined') {
            document.write('<script src="/path/to/local/jquery.min.js"><\/script>');
        }
    </script>

In this code snippet, we first attempt to load jQuery from the CDN. Then, we check if the jQuery object is defined. If it’s not (i.e., jQuery is not loaded), we load jQuery from a local file using the document.write method.

Conclusion

It’s crucial to make sure jQuery is loaded on your webpage before executing any jQuery-dependent code. You can check if jQuery is loaded using the browser console, within your JavaScript code, or by implementing a fallback option. By following these methods, you’ll ensure that your webpage functions correctly with the power of jQuery.