Form validation means checking user input before sending it to the server. This helps make sure the data entered is correct, complete, and safe.
JavaScript allows you to validate forms instantly, without waiting for the page to reload. This improves user experience and prevents common mistakes like empty fields or invalid data.
Form validation is a must-have skill for every front-end developer.
What JavaScript Validation Can Check
- Empty fields
- Correct email format
- Password length
- Number ranges
- Required checkboxes
- Matching values (like password confirmation)
These checks protect both users and applications.
This simple form has one input field and a submit button.
JavaScript will be used to check if the user entered a value before submitting.
This script checks if the name field is empty when the form is submitted.
If it is empty, the form submission is stopped and an alert message is shown.
These examples show how JavaScript can check user input before it is sent.
By mastering form validation, students gain the ability to build secure, user-friendly, and professional web forms for real-world applications.