How to Perform Form Validation in JavaScript?

In this article, I will explain How to Perform Form Validation in JavaScript.

Basically, form validation is the task of checking the user input data on a web form. It ensures that the user input meets certain criteria before it is submitted to the server. Moreover, form validation helps us to prevent invalid or malicious data from being sent to the server. Also it helps to ensure that the data entered into the form

(i) is in the correct format.

(ii) It meets certain requirements (such as minimum length, data type, etc.)

(iii) It is free of errors.

Steps to Perform Form Validation in JavaScript

In fact, we perform form validation on the client-side using JavaScript. However, we can do it on the server-side using a server-side scripting language like PHP, Ruby, or Python. In order to perform form validation in JavaScript, you can follow these steps:

1. At first, get the form element using document.getElementById(). Basically, this function retrieves the form in a variable in JavaScript.
2. After that, get the input elements within the form using elements property. Actually, the elements property returns a collection of all the elements in the form.
3. Once, we retrieve elements, we can process them. So, loop through the input elements. When performing loop iterations, check their values using conditions. So, you can check whether the values are valid or not.
4. Show error messages if the values are not valid
5. Return false if any error is found, else return true to submit the form.

function validateForm() {
  var form = document.getElementById("form");
  var inputs = form.elements;
  for (var i = 0; i < inputs.length; i++) {
    if (inputs[i].value == "") {
      alert("All fields are required");
      return false;
    }
  }
  return true;
}

Further Reading

Evolution of JavaScript from ES1 to ES2020

Introduction to HTML DOM Methods in JavaScript

JavaScript Practice Exercise

Understanding Document Object Model (DOM) in JavaScript

Understanding HTTP Requests and Responses

What is Asynchronous JavaScript?

JavaScript Code for Event Handling

• Angular
• ASP.NET
• Bootstrap
• C
• C#
• C++
• CSS
• Deep Learning
• Django
• Dot Net Framework
• HTML
• IoT
• Java
• JavaScript
• Kotlin
• MEAN Stack
• MERN Stack
• MongoDB
• NodeJS
• PHP
• Power Bi
• Projects
• Python
• Scratch 3.0
• SQL
• TypeScript
• VB.NET
• Web Designing
• XML

Princites