JS Junction

Web APIs

JS Web Validation API

Form Validation with JavaScript

JavaScript Web Validation API uses checkValidity for form checks.

Introduction to the Web Validation API

The JavaScript Web Validation API provides a way to validate HTML forms before submission. It is built into browsers, allowing developers to ensure that user inputs meet the specified requirements without requiring server-side validation.

Understanding checkValidity Method

The checkValidity() method is a core part of the Web Validation API. This method checks whether an input element complies with its validation constraints and returns a boolean value: true if the input is valid, and false if not. When an input is invalid, the browser can display a validation message.

Here is the basic syntax for using checkValidity():

Example: Validating a Simple Form

Let's look at an example where we validate a simple form with a text input and an email input. We'll use checkValidity() to ensure both fields are filled before allowing form submission.

Custom Validation Messages

Sometimes, the default validation messages provided by the browser are not sufficient for user understanding. JavaScript allows you to customize these messages using the setCustomValidity() method. You can provide a custom message that will be displayed when the input is invalid.

Conclusion

The JavaScript Web Validation API simplifies client-side form validation, ensuring that input fields meet the required criteria before submission. By using checkValidity() and setCustomValidity(), developers can effectively manage form validation and provide a better user experience. For more advanced usage, explore additional features such as the Constraint Validation API.

Web APIs

Next
Web Speech API