Resolving Uncaught ReferenceError: firstFunc is not defined in WordPress Divi

Are you facing `Uncaught ReferenceError: firstFunc is not defined` when trying to implement JavaScript in WordPress Divi? Discover the solutions and best practices in our detailed guide, tailored for beginners in web development.
---
This video is based on the question https://stackoverflow.com/q/72280186/ asked by the user 'ybyonas' ( https://stackoverflow.com/u/19139809/ ) and on the answer https://stackoverflow.com/a/72280372/ provided by the user 'tacoshy' ( https://stackoverflow.com/u/14072420/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Uncaught ReferenceError: firstFunc is not defined at HTMLButtonElement.onclick Wordpress Divi

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Resolving Uncaught ReferenceError: firstFunc is not defined in WordPress Divi: A Beginner's Guide

If you’re new to web development, encountering issues with your code can be quite frustrating. One common issue users face while working with JavaScript in WordPress, especially in Divi, is the error message: Uncaught ReferenceError: firstFunc is not defined. In this post, we will explore what causes this error and how to solve it effectively.

Understanding the Problem

The error indicates that the JavaScript function firstFunc() is not recognized when it is called, such as when a button is clicked. This can happen due to a variety of reasons, including typos in your code, incorrect function definitions, or misused JavaScript methods.

The Coding Attempt

Let’s consider an example code snippet:

[[See Video to Reveal this Text or Code Snippet]]

Identifying the Issues

Upon examining the code, we can spot several issues that could be causing the error:

Semicolon Errors:

The semicolon in the if condition should be removed.

Incorrect placement of semicolon and brace which should be corrected.

Misused JavaScript Methods:

There is no getElementByClass. The correct method to use is getElementsByClassName.

For targeting a single element, we suggest using querySelector instead.

Here’s how you can fix these issues:

Corrected Code

Below is a corrected version of the function:

[[See Video to Reveal this Text or Code Snippet]]

Improving Your Code with CSS

While the above code will work, there is a smarter way to implement background and text color changes using JavaScript and CSS together. Instead of directly manipulating the styles in JavaScript, we can use CSS classes for better structure and maintainability.

Suggested Approach

Add CSS Class for the Active State:

Define a CSS class that toggles the button's appearance:

[[See Video to Reveal this Text or Code Snippet]]

JavaScript Function Using classList.toggle:

Modify the JavaScript function to use classList.toggle:

[[See Video to Reveal this Text or Code Snippet]]

Final HTML Snippet

Here's how the final button and script should look:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

The error Uncaught ReferenceError: firstFunc is not defined can be resolved by correcting syntax issues and using the right JavaScript methods. By incorporating CSS classes, you not only solve the problem but also follow best coding practices that lead to more maintainable and scalable code.

As a beginner in web development, remember that coding is a learning process – don’t hesitate to seek help and keep experimenting. Happy coding!