Handling User Input with Form Handling Techniques

Form handling techniques are essential for any web page that requires user input, and they allow you to process and validate user input before it is submitted. In this article, we’ll take a closer look at how to handle user input with form handling techniques in HTML.

HTML Forms

Forms are used to collect user input, and they are denoted by the <form> element.

Here’s an example of how to create a form in HTML:

<form action="/process-form.php" method="post">
  <input type="text" name="username" placeholder="Enter your username">
  <input type="password" name="password" placeholder="Enter your password">
  <button type="submit">Log in</button>
</form>

In this example, we have created a form using the <form> element and added two input fields and a button. We have also specified the action attribute with the URL of the script that will process the form, and the method attribute with the HTTP method to use when submitting the form.

Form Validation

Form validation is the process of checking that user input is valid before it is submitted.

There are various techniques that you can use to validate user input in HTML, including client-side and server-side validation.

Client-side validation is performed by the web browser, and it is generally faster and more efficient than server-side validation. However, it is also less secure, as users can disable or bypass client-side validation.

Server-side validation is performed by the web server, and it is generally slower and less efficient than client-side validation. However, it is also more secure, as users cannot disable or bypass server-side validation.

HTML provides various attributes that you can use to validate user input, including:

• required: specifies that the input field is required
• pattern: specifies a regular expression that the input field must match
• min and max: specify the minimum and maximum values that the input field can have

Here’s an example of how to use the required attribute to validate user input in HTML:

<input type="text" name="username" 
placeholder="Enter your username" required>

In this example, we have added the required attribute to the input field, which specifies that the input field is required and that the user must enter a value.

Here’s an example of how to use the pattern attribute to validate user input in HTML:

<input type="text" name="email" 
placeholder="Enter your email" 
pattern="[a-z0-9._%+-]+@[a-z0-9.-]+\.[a-z]{2,}$">

In this example, we have added the pattern attribute to the input field, which specifies a regular expression that the input field must match. In this case, the regular expression specifies that the input must be a valid email address.

Here’s an example of how to use the min and max attributes to validate user input in HTML:

<input type="number" name="age" 
placeholder="Enter your age" min="18" max="120">

In this example, we have added the min and max attributes to the input field, which specify the minimum and maximum values that the input field can have. In this case, the input field can only accept values between 18 and 120.

Form Processing

Form processing is the process of handling the user input after it has been submitted.

There are various techniques that you can use to process user input in HTML, including client-side and server-side processing.

Client-side processing is performed by the web browser, and it is generally faster and more efficient than server-side processing. However, it is also less secure, as users can disable or bypass client-side processing.

Server-side processing is performed by the web server, and it is generally slower and less efficient than client-side processing. However, it is also more secure, as users cannot disable or bypass server-side processing.

HTML provides various methods that you can use to process user input, including:

• GET: sends the data in the form as a query string in the URL
• POST: sends the data in the form as a request body

Here’s an example of how to use the POST method to process user input in HTML:

<form action="/process-form.php" method="post">
  <input type="text" name="username" placeholder="Enter your username">
  <input type="password" name="password" placeholder="Enter your password">
  <button type="submit">Log in</button>
</form>

In this example, we have specified the POST method in the form using the method attribute, and we have specified the URL of the script that will process the form using the action attribute. When the user submits the form, the data will be sent as a request body to the specified URL.

Conclusion

Form handling techniques are essential for any web page that requires user input, and they allow you to process and validate user input before it is submitted. With the skills and knowledge you gain in this course, you’ll be able to create professional-quality forms that are easy to use and secure.

Exercises

To review these concepts, we will go through a series of exercises designed to test your understanding and apply what you have learned.