Forms are used to collect user input. JavaScript helps you validate this input before it gets submitted, ensuring that only correct data is processed.

JavaScript can check if a form field is empty or has the correct format before allowing submission. This prevents users from submitting incomplete or incorrect information.

Syntax:
onsubmit="return validateForm()"

HTML5 allows you to validate input automatically using built-in attributes like required, type, min, max, and pattern. No JavaScript is needed for basic validation.

You can use JavaScript to check whether the user entered a number within a specific range or if the input is even a number at all.