How to Fix the Undefined Error When Saving Data from an HTML Form

Discover the key steps to troubleshoot and resolve the `undefined` error when saving form data using JavaScript.
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Fixing the Undefined Error in Your HTML Form Submission

Collecting user data via a sign-up form is a common scenario in web development. However, it can be frustrating when you encounter an undefined error in your browser while trying to retrieve input values. If you've been struggling with this issue, fear not—this guide will walk you through identifying the problem and implementing a definitive solution.

The Problem: Understanding the Undefined Error

When users click the "Sign Up" button, you expect the JavaScript code to retrieve their input values. Instead, you're getting an undefined error. This typically happens due to a misunderstanding of how DOM methods work.

The Solution: Correctly Accessing Input Values

To properly retrieve the input values from your form, follow these steps:

Method 1: Accessing the First Input

If you're only interested in the first input with the class loginInfo, you can modify your JavaScript like so:

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

Method 2: Using querySelector

If your form contains multiple inputs and you want to retrieve all their values, querySelector might be a better option. It allows you to simplify the code further. Here's how:

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

Retrieving Multiple Inputs

To capture each input separately, you can iterate over the collection of elements returned by getElementsByClassName. Here's an example:

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

Summary of Key Points

Error Source: Using getElementsByClassName directly on a collection yields an undefined value.

Recommended Fixes:

Loop through the collection for multiple inputs to gather all values.

By following these instructions, you should be able to resolve the undefined error and successfully save user data from your HTML form. Happy coding!