JavaScript Form Validation

JavaScript Form Validation is a way to ensure that the data users enter into a form is correct before it gets submitted. This helps ensure that things like emails, passwords, and other important details are entered properly, making the user experience smoother and the data more accurate.

Steps for Form Validation in JavaScript

When we validate a form in JavaScript, we typically follow these steps:

• Data Retrieval:
  • The first step is to get the user’s values entered into the form fields (like name, email, password, etc.). This is done using document.forms.RegForm, which refers to the form with the name “RegForm”.
  • Data Validation:
    • Name Validation: We check to make sure the name field isn’t empty and doesn’t contain any numbers.
    • Address Validation: We check that the address field isn’t empty.
    • Email Validation: We make sure that the email field isn’t empty and that it includes the “@” symbol.
    • Password Validation: We ensure that the password field isn’t empty and that the password is at least 6 characters long.
    • Course Selection Validation: We check that a course has been selected from a dropdown list.
    • If any of the checks fail, an alert message is shown to the user using window.alert, telling them what’s wrong.
    • The form focuses on the field that needs attention, helping the user easily fix the error.
    • If all the validation checks pass, the function returns true, meaning the form can be submitted. If not, it returns false, stopping the form from being submitted.
    • The form automatically focuses on the first field that has an error, guiding the user to fix it.

    Example: Here is an example of above explained approach.

                                                                                                            JavaScript

    Output:

    Types of Form Validation

    • Client-side Validation:
      • This is done in the user’s browser before the form is submitted. It provides quick feedback to the user, helping them fix errors without sending data to the server first.
      • Server-side Validation:
        • Even though client-side validation is useful, it’s important to check the data again on the server. This ensures that the data is correct, even if someone tries to bypass the validation in the browser.

        Various Use case

        Below are the some use cases of Form Validation in JavaScript.

        1. Form validation using jQuery

        Here, we have validated a simple form that consists of a username, password, and a confirmed password using jQuery,

        2. Number validation in JavaScript

        Sometimes the data entered into a text field needs to be in the right format and must be of a particular type in order to effectively use the form. For instance, Phone number, Roll number, etc are some details that must be in digits not in the alphabet.

        3. Password Validation Form Using JavaScript

        The password Validation form is used to check the password requirements such as the password must have at least one Uppercase, or lowercase, number, and the length of the password.

        4. How to validate confirm password using JavaScript ?

        You can validate a confirm password field using JavaScript by comparing it with the original password field.

        5. JavaScript Program to Validate Password using Regular Expressions

        A Regular Expression is a sequence of characters that forms a search pattern. The search pattern can be used for text search and text to replace operations. A regular expression can be a single character or a more complicated pattern.