How to Fix Field Level Validation Issues in Your JavaScript Forms

Learn how to effectively handle `field level validation` in JavaScript forms and ensure your users receive proper feedback before submit.
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Troubleshooting Field Level Validation in JavaScript Forms

As a budding developer, crafting forms can sometimes feel overwhelming, especially when it comes to handling user inputs properly. One common problem that many face is ensuring that form fields, like the First Name, validate correctly before submission. In this guide, we'll shed light on how to fix issues with field level validation using JavaScript, particularly taking a closer look at a snippet that isn’t functioning as expected.

The Problem

You might be wondering why your First Name field is allowing the form to submit even when the user hasn't entered a name. This is a frequent issue for beginners attempting to implement form validation. Let's take a look at the key parts of your code that might be causing this problem:

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In this example, the firstNameValid function checks whether the firstName variable is empty. If it is, an alert is shown, but the form still submits because the function isn't properly linked to the submission event.

The Solution

1. Adjust the Function Call

One of the main issues in your code is that the firstNameValid() function does not return a value back to the validateForm() function. This means that even if firstNameValid() alerts the user, it doesn’t prevent form submission. Here's how you can revise the code to fix this:

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

Now, the validateForm() function will return false if firstNameValid() checks the name and finds it empty, thus preventing the form from submitting.

2. Correct Script Tag Usage

The second issue lies in how the <script> tag is being included in your HTML. Ensure that your JavaScript file is imported correctly like this:

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Avoid the following erroneous format that may confuse the browser:

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3. HTML Structure

The general structure of your HTML should look like this, with the updated JavaScript import:

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Conclusion

Field level validation is essential to ensure that user input meets the necessary criteria before form submission. By returning the result from your validation check and ensuring that your script is correctly linked, you can avoid common issues that come with form handling. With these adjustments, your First Name validation should now work flawlessly. Happy coding!