What is Client Side Validation?


What is Client Side Validation?

In software development, one of the often faced challenges is the ability to mitigate bottlenecks and user errors. Well, the approach that most developers employ to address the issue is form validation, a technical procedure where a web form runs a check to understand whether or not the data provided by a user is correct.

Furthermore, it’s worth knowing that form validation can be achieved in a couple of ways; Server-side Validation and Client-side Validation. The first approach – a server-side validation is a process that occurs on the server after the information has been submitted.

Client-side validation, on the other hand, is the user input validation that occurs on the client’s side. It’s the type of validation that’s carried out in the browser, ensuring that information entered is in the right format and within the constraints set by the app.

Client-side validation offers end users a smooth experience. Apart from that, it also tries as much as possible to reduce loads from the server. In the rest of this article, you’ll find out everything you need to know about client-side validation, including its benefits and how to implement it. So, without further ado, let’s get straight down to business.

What Is Form Validation?

For you to fully understand what client-side validation is all about, let’s start by talking about form validation.

You’ll surely agree with me that forms are ever-present in web applications. They are always there to perform several different functions.

For instance, some people choose to add forms to their apps to collect sign-up data from their users. Apart from that, many others make use of them to perform online transactions for a better shopping experience. For the best results, all data received during these processes need to be cleaned, properly formatted, and free of any malicious code. Here’s where “form validation” comes into the scene.

Form validation is a technical process where checks are performed on web forms to ascertain that the information provided by users is properly formatted and useful. During the process, if the system finds the data correct, it validates the information and allows the end-user to continue with the rest of the registration. However, if the system finds the data in a poor format, it’ll immediately signal the user to fix up the error.

There are tons of benefits attached to having a good form validation measure in place. First, it helps to ensure that the user enters the right data, using the proper format. Furthermore, form validation also helps to secure users’ data. That’s not all; the validation process will ensure that your application is secured from malicious users.

As earlier mentioned, there are two types of form validation – server-side validation and client-side validation. For the sake of this post, I’ll only focus my attention on the latter.

What Is Client-Side Validation?

Client-side validation is the type of validation that occurs in the browser or the web server. The system ensures that the end-user is entering the right data in the right format.

If after checking, the system finds out that the information provided by the user is correctly formatted, it proceeds to validate it. It does that by allowing the data to be submitted and stored in the server’s database. However, if the data comes out incorrect, the system will provide an error message, alerting the user to adjust where necessary.

How exactly does the client-side form validation work?

Now that you’ve gotten a clear picture of what client-side form validation is all about, let’s make things clearer by talking about how it works.

As you now know, the client-side validation occurs in the browser, before the data gets submitted to the server. Below is a brief explanation of how the validation process occurs:

  • The process often starts with a user, who needs to register on the web, filling the form.
  • Upon completion, the browser will proceed to validate the data. If it finds the information incorrect, it’ll respond with an error message without having to wait for the server.
  • The bottom line is, the browser is only capable of forwarding valid data to the server. So, if the user inputs the right data in the proper format, the browser will immediately validate it, send it to the server and then receive a response from the server.

I’m sure you must have come across an error message that says;

“Your password needs to be between 6 and 30 characters long. It must contain at least one uppercase, at least one lowercase letter, at least one numeric digit, and at least one special character.”

The above example is a type of form validation that occurs in the browser – client-side validation. This error message will keep popping up until the user inputs the correct data, in the right format.

What are the different types of client-side form validation?

When it comes to the validation of users’ data from the client’s side, there are two different types of ways to go about it. You can use both the built-in form validation and the JavaScript validation techniques. That said, let’s take a look at each of them below:

  1. Built-in form validation

Built-in form validation is a process that utilizes HTML5 form validation features. The interesting thing about this approach is that it doesn’t require much JavaScript.

Furthermore, built-in form validation utilizes HTML5 form controls. This offering makes it easy to validate most user data without necessarily using JavaScript. That said, you can check below to see some of the elements that the built-in validation technique uses:

  • required: This element makes it possible for your browser to show an error when an important field on the form is left blank.
  • “minlength” and “maxlength”: These elements help to ensure that a user can understand the minimum and maximum length of characters.
  • “type”: This element helps the browser to specify whether the user needs to enter a number or email address.
  1. JavaScript validation

Unlike built-in form validation, JavaScript validation requires much JavaScript. Interestingly, you can always customize error messages with this technique.

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