Excluding Specific Email Patterns in Form Submissions

When building web forms, it’s essential to validate user input to ensure data integrity. One common validation task is excluding specific email patterns from being submitted.

In this blog post, we’ll discuss how to achieve this using regular expressions.

The Problem

Suppose you have a web form where users can submit their email addresses.

However, you want to exclude email addresses from specific domains, such as gmail.com, yahoo.com, and outlook.com. How can you achieve this?

Solution: Regular Expressions

Regular expressions (regex) are powerful tools for pattern matching. We can use regex to define a pattern that matches valid email addresses while excluding specific domains.

The Regex Pattern

The regex pattern to exclude specific email domains is as follows:

^(?!.*@(?:gmail\.com|yahoo\.com|outlook\.com)).*$

Let’s break down the pattern:

^ and $ indicate the start and end of the string, respectively.
(?!...) is a negative lookahead assertion, ensuring that the email address does not contain any of the specified domains.
.* allows any other valid domain to be accepted.

Implementation

To implement this in your form validation logic, follow these steps:

1. HTML Page

Create an HTML form with an input field for the email address.

Add a submit button to trigger the validation.

<form onsubmit="return validateEmail()">

    <label for="email">Email:</label>

    <input type="email" id="email" name="email" required>

    <button type="submit">Submit</button>

</form>

2. JavaScript Page (validate_email.js)

Create a JavaScript file (validate_email.js) to handle the form submission and email validation.

function validateEmail() {
    const emailInput = document.getElementById('email');
    const emailPattern = /^(?!.*@(?:gmail\.com|yahoo\.com|outlook\.com)).*$/;

    const email = emailInput.value.trim();

    if (emailPattern.test(email)) {
        // Valid email address
        window.location.href = "#"; // Uncomment this line
        return false; // This line prevents default form submission
    } else {
        // Invalid email address
        alert('Please enter a valid email address excluding Gmail, Yahoo, or Outlook domains.');
        return false;
    }
}

3. Testing

Test the form by entering different email addresses:

Valid email: john.doe@example.com
Invalid email: john.doe@gmail.com

Here is a demo link: Validate Email

In conclusion, by implementing this solution, you can exclude specific email domains from being submitted via your web form.

Remember to adjust the pattern according to your specific requirements and domain exclusions.

Disclaimer:

The code snippet provided here is intended for educational purposes and as a starting point for understanding email validation techniques. It is not a one-size-fits-all solution, and I strongly recommend that you customize and adapt it to your specific use case. Before implementing any code on your website, consider the following:

Understand the Code: Take the time to comprehend how the code works. Don’t blindly copy and paste it without understanding its logic.
Professional Implementation: While this snippet demonstrates a basic approach, consult a professional developer to ensure proper integration into your site. They can address any nuances related to your platform, security, and scalability.
Risk of Breaking Your Site: Incorrect implementation can lead to issues like false rejections of valid emails or acceptance of invalid ones. Use with caution and thoroughly test in a staging environment before deploying it on your live site.

Remember that every website has unique requirements, and what works well for one may not suit another. Always prioritize security, user experience, and reliability when implementing any code.

Happy coding! 🚀

Mastering Data Integrity: How to Exclude Specific Email Patterns in Web Form Submissions