Скачать или смотреть Resolving the Issue of CSS Error Class Not Applying in JavaScript Form Validation

A guide to fix the JavaScript function that adds a CSS error class to form fields during validation, ensuring seamless user feedback.
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This video is based on the question https://stackoverflow.com/q/68067978/ asked by the user 'Zenz' ( https://stackoverflow.com/u/10386136/ ) and on the answer https://stackoverflow.com/a/68070636/ provided by the user 'Gaurish Kamat' ( https://stackoverflow.com/u/8887814/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Fixing the Issue with CSS Error Class in JavaScript Form Validation

When creating web forms, validating user input before submission is crucial for both user experience and data integrity. In the case where you have implemented JavaScript validation for a contact form and found that your CSS error class isn't properly applying, don't worry! This guide will break down the problem and guide you through the necessary steps to ensure your error messaging works effectively.

Understanding the Problem

You've created a contact form with JavaScript validation that alerts the user of any errors in their input. However, while the validation logic seems sound, you notice that the error messages or CSS styles (like the red border and error icons) aren't displayed correctly when validation fails. This can confuse users, as they won't be notified of any issues with their submissions.

Breaking Down the Solution

Identifying Errors in Your Code

The main logic responsible for displaying the validation errors is found in the setErrorFor function. Let's identify some common pitfalls:

HTMLCollection vs. Array: The method getElementsByClassName returns an HTMLCollection, not an Array. You'll need to convert this collection to an Array to utilize array methods like forEach.

Correct Element Reference: When using forEach, make sure you're applying changes to individual elements of the Array, not to the whole collection.

Steps to Fix Your Code

Here’s a simplified breakdown of what you need to correct in your setErrorFor function.

1. Convert HTMLCollection to Array

Instead of working with the HTMLCollection directly, use Array.from() to create an Array. This will allow you to use the forEach method seamlessly.

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2. Update Looping Logic

While iterating through the small elements, ensure you update the text of each small element correctly. Currently, you attempt to update small.innerText; instead, reference the element:

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Updated setErrorFor Function

Here’s what your corrected setErrorFor function may look like:

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3. Test Your Changes

After making these corrections, test your form again. Submit with empty fields to see if the error messages now display correctly. You should see the error borders, icons, and custom messages as intended.

Conclusion

Debugging form validations can be tricky, but understanding how JavaScript interacts with the DOM can help alleviate many issues. By ensuring you're using the correct methods to manipulate the error messages and visibility, you'll provide your users with a reliable and informative form submission experience.

If these adjustments don’t resolve your issues, consider exploring other areas of your code or browser compatibility issues. Happy coding!