Resolving the addEventListener is not a function Error in JavaScript

Learn how to fix the `addEventListener is not a function` error in JavaScript by using the right element selection technique and event handling. --- This video is based on the question https://stackoverflow.com/q/64798930/ asked by the user 'Venkat Raman Behera' ( https://stackoverflow.com/u/14623835/ ) and on the answer https://stackoverflow.com/a/64799129/ provided by the user 'Durgesh' ( https://stackoverflow.com/u/4613438/ ) 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: showing error -- addEventListener is not a function 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 the addEventListener is not a function Error in JavaScript When working on a JavaScript project, encountering errors can be a common hurdle. One particularly frustrating issue is the error message: addEventListener is not a function. This typically occurs when attempting to add an event listener to a button (or any HTML element) incorrectly. In this guide, we’ll explore the reasons behind this error and how to fix it using clear, step-by-step instructions. Understanding the Error The error message you might encounter when trying to run a script could look something like this: [[See Video to Reveal this Text or Code Snippet]] What Causes This Error? This error primarily occurs when attempting to call addEventListener() on a collection of elements returned by getElementsByTagName(). Here’s the key point: getElementsByTagName() returns a NodeList, which is an array-like collection of elements. Because of this, if you try to call addEventListener() directly on the NodeList, JavaScript doesn't know what to do with it and throws an error. Example of Typical Mistake Here’s a snippet from a sample HTML and JavaScript code that can trigger this error: [[See Video to Reveal this Text or Code Snippet]] In the code above, boton refers to a NodeList, hence addEventListener() is not a valid function to call directly on it. The Solution: Correctly Accessing the Button Element To resolve this issue, you need to correctly access the specific button element you want to add the event listener to. Here’s how to do that: Step 1: Accessing the Button Since getElementsByTagName() retrieves a collection, you need to specify which button you want to work with. You can index into the returned NodeList: [[See Video to Reveal this Text or Code Snippet]] Step 2: Complete Code Example Here is a complete example that successfully incorporates the solution: [[See Video to Reveal this Text or Code Snippet]] Additional Tips Using More Descriptive Names: It can be beneficial to use more descriptive variable names to ensure that your code is clear. Instead of boton, consider naming it buttons or buttonList to reflect that it's a collection. Debugging Techniques: If you're ever in doubt about what your variables contain, use console.log() to print them out in the console. This will help clarify whether you're working with the right objects. Conclusion The addEventListener is not a function error can catch even seasoned developers off guard. However, by understanding how to correctly reference the elements you want to interact with, you can avoid this roadblock. Ensure that you're selecting the specific element you mean to target and take time to review your code if similar issues come up in the future. Happy coding!