JavaScript Form Validation Library

Introduction to JavaScript Form Validation Library

Form validation is an essential step in building a robust and user-friendly web application. It ensures that the user input data is accurate, complete, and valid before submitting the form to the server. In this tutorial, we will explore how to use the JavaScript Form Validation Library, a popular and widely-used library for form validation.

What is the JavaScript Form Validation Library?

The JavaScript Form Validation Library is a lightweight and easy-to-use library that provides a set of methods and functions to validate form inputs. It supports various types of form fields, including text inputs, checkboxes, radio buttons, select boxes, and more. The library also provides a flexible and customizable way to validate form data, allowing developers to define their own validation rules and messages.

Getting Started with the JavaScript Form Validation Library

To get started with the JavaScript Form Validation Library, you need to include the library's JavaScript file in your HTML file. You can download the library from the official website or include it from a CDN.

Here's an example of how to include the library in your HTML file:

<script src="https://cdn.jsdelivr.net/npm/form-validation@1.3.0/dist/form-validation.min.js"></script>

Using the JavaScript Form Validation Library

Once you have included the library in your HTML file, you can use it to validate your form data. Here's a step-by-step guide on how to use the library:

Step 1: Create a Form

Create a form in your HTML file with the fields you want to validate. For example:

<form id="myForm">
  <label for="name">Name:</label>
  <input type="text" id="name" name="name"><br><br>
  <label for="email">Email:</label>
  <input type="email" id="email" name="email"><br><br>
  <label for="phone">Phone:</label>
  <input type="tel" id="phone" name="phone"><br><br>
  <input type="submit" value="Submit">
</form>

Step 2: Initialize the Form Validation Library

Initialize the form validation library by calling the formValidation function and passing the form element as an argument. For example:

const form = document.getElementById('myForm');
const formValidation = new FormValidation(form);

Step 3: Define Validation Rules

Define validation rules for each form field using the addRule method. For example:

formValidation.addRule('name', 'required');
formValidation.addRule('email', 'email');
formValidation.addRule('phone', 'phone');

In this example, we're defining three validation rules:

• The name field is required.
• The email field must be a valid email address.
• The phone field must be a valid phone number.

Step 4: Validate the Form

Call the validate method to validate the form data. For example:

formValidation.validate().then((isValid) => {
  if (isValid) {
    // Form is valid, submit the form
    form.submit();
  } else {
    // Form is invalid, display error messages
    formValidation.getErrorMessages();
  }
});

In this example, we're calling the validate method to validate the form data. If the form is valid, we submit the form. If the form is invalid, we display the error messages using the getErrorMessages method.

Step 5: Handle Error Messages

Handle error messages by displaying them to the user. You can use the getErrorMessages method to get an array of error messages for each form field. For example:

const errorMessages = formValidation.getErrorMessages();
errorMessages.forEach((message) => {
  console.log(message);
});

In this example, we're logging the error messages to the console. You can display the error messages to the user in a more user-friendly way, such as using HTML elements or a JavaScript library.

Conclusion

In this tutorial, we have learned how to use the JavaScript Form Validation Library to validate form data. We have covered the basics of the library, including how to initialize it, define validation rules, validate the form, and handle error messages. With this library, you can easily validate your form data and provide a better user experience for your users.