5 Ways to Implement Email Validation in jQuery

Validating email addresses is key to ensuring data quality and successful user sign-ups. We'll explore five ways to handle this in jQuery, providing working code for each. You'll also see the common pitfalls of these methods and how Abstract API offers a more robust solution.

How to Implement Email Validation in jQuery

Here are four common methods to validate email addresses with jQuery. Each technique approaches the problem differently, from simple pattern matches to more complex server-side checks.

Direct Regex in a jQuery Handler

This approach attaches an event handler, like `blur` or `submit`, to a form element. When the event fires, it tests the input value against a regular expression. The regex pattern attempts to match the standard format of an email address. If the test fails, the code can prevent form submission or show an alert.

const emailRx = /^(([^<>()[\]\\.,;:\s@"]+(\.[^<>()[\]\\.,;:\s@"]+)*)|(".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z-0-9]+\.)+[a-zA-Z]{2,}))$/;
$('form').on('submit', e => {
    const v = $('#email').val();
    if (!emailRx.test(v)) { e.preventDefault(); alert('Bad address'); }
});

HTML5 Input Type and the DOM Validity API

This method relies on the browser's native validation for inputs with `type="email"`. jQuery hooks into the `invalid` and `input` events. The `invalid` event fires when the value is not a valid email, which allows you to add an error class. The `input` event lets you remove the error class once the user corrects the entry.

$('#email')
    .attr('type', 'email')               // modern browsers validate automatically
    .on('invalid', function () { $(this).addClass('error'); })
    .on('input',  function () {
        if (this.checkValidity()) $(this).removeClass('error');
    });

The jQuery-Validation Plugin

A popular choice is the jQuery-validation plugin, which includes a pre-built email validation rule. You initialize the plugin on your form with the `validate` method. Inside, you specify rules for each field, such as `required: true` and `email: true`. The plugin handles the validation logic and displays custom error messages you define.

$('#myForm').validate({
    rules:   { email: { required: true,  email: true } },
    messages:{ email: 'Please supply a valid address.' }
});

Remote AJAX Validation

This technique uses the jQuery-validation plugin's `remote` rule to perform an asynchronous check. When the user enters an email, the plugin sends an AJAX request to a server-side script you specify. The script validates the email and must return a simple true or false response. The plugin then marks the field as valid or invalid based on this server response.

$('#myForm').validate({
    rules: {
        email: {
            required: true,
            email: true,
            remote: { url: '/check-email.php', type: 'post' }
        }
    }
});

Challenges of jQuery Email Validation

While these client-side methods offer quick feedback, they share fundamental limitations that can compromise data quality. These approaches often fail to account for the full complexity of modern email standards.

• Regex patterns, used in direct handlers and the validation plugin, cannot parse all valid formats. They often reject compliant addresses with quoted parts or IP-literal hosts, which makes them unreliable and difficult to maintain.
• Client-side scripts cannot query DNS records to confirm a domain's mail servers. Methods like direct regex or the HTML5 input type only check syntax, not actual deliverability, and require constant updates for new TLDs.
• Internationalized addresses with non-ASCII characters expose browser inconsistencies. The HTML5 email input type and common regex patterns often reject valid Unicode local parts or domains, which frustrates international users.
• Common email conventions like plus-addressing or internal domains without a TLD often cause validation failures. Regex-based approaches force a choice between leaky validation or a patchwork of complex exceptions to handle these cases.