Скачать или смотреть Custom Client Side Validation: Implementing JavaScript in MVC 5 Forms

Learn how to implement `custom client side validation` in MVC 5 forms using JavaScript and jQuery, ensuring user input meets the required standards.
---
This video is based on the question https://stackoverflow.com/q/75087361/ asked by the user 'TEJUS SHUKLA' ( https://stackoverflow.com/u/20982793/ ) and on the answer https://stackoverflow.com/a/75087445/ provided by the user 'mplungjan' ( https://stackoverflow.com/u/295783/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Custom Client Side Validation through JavaScript

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Custom Client Side Validation in MVC 5 Forms

When developing web applications, one crucial aspect to focus on is ensuring that user input is valid before submitting forms. This not only improves user experience but also helps in maintaining data integrity in your application. In this guide, we'll discuss how to implement custom client-side validation in MVC 5 forms using JavaScript and jQuery.

Understanding the Problem

In MVC (Model-View-Controller) applications, you often need to validate user input. In particular, let's consider a scenario where you have a form with fields for a student's first name, last name, phone number, and email. Imagine that you need to restrict the input for the phone number field to numbers only. If a user mistakenly inputs letters or special characters, we want to display an error alert or message.

While MVC provides server-side validation, customizing this validation client-side enhances the user experience by catching errors before submission. In this example, we focus on the phone input field where we want to enforce these rules.

Solution Breakdown

To implement custom client-side validation, follow these steps:

Step 1: Set Up Your Form

Make sure your form is set up correctly in your Razor view. It should look similar to the following structure (based on the provided code). Pay special attention to the EditorFor method, which allows you to attach attributes to the input elements.

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Attach JavaScript for Validation

To enable custom validation, you need to listen for changes in the phone input field. You'll attach an event handler to check the input as the user types.

Here’s a refined version of your JavaScript code to handle the validation logic correctly:

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Execution Flow

Initialization: When the page loads, the jQuery function initializes and sets up an event listener on the phone input field.

Input Handling: As the user types in the phone field, the input event triggers the callback function.

Validation logic: Inside the callback function:

Extract the current value of the input field.

Use a regular expression to check if the input contains only digits.

If invalid (contains letters or special symbols), show an alert and clear the input field.

Optional Step: Server-Side Validation

While client-side validation is essential, you should always implement server-side validation as well. This protects against users bypassing client checks and ensures data integrity in your application.

Conclusion

Implementing custom client-side validation in MVC 5 forms significantly enhances user experience by providing immediate feedback. With the proper structure in your Razor view and effective JavaScript handling, you can easily ensure that users are entering valid data. Use the provided example to set up similar validation for other fields in your application, custom-tailoring the messages based on specific needs.

By taking the time to ensure the validity of user inputs, you help create a more robust and user-friendly application. Happy coding!