JavaScript form validation is the process of ensuring that user input in forms meets specific requirements before it’s submitted to a server. It improves user experience by providing instant feedback and reduces server-side validation load. Validation can check if fields are filled, emails are formatted correctly, passwords meet complexity rules, or numerical values fall within a range. With JavaScript, you can add event listeners to form elements to validate data in real-time. For instance, you might disable a submit button until all required fields are valid. Modern approaches often leverage the Constraint Validation API, which simplifies tasks with attributes like required or pattern.
