5 Ways to Implement Phone Number Validation in jQuery

Validating phone numbers is a basic requirement for forms using jQuery to maintain data integrity. Explore four distinct validation methods, each with functional code examples. Following that, we analyze the drawbacks of these standard methods and show how Abstract API solves these specific problems.

How to Implement Phone Number Validation in jQuery

Here are three common methods to validate phone numbers with jQuery. Each approach uses a different technique, from regular expressions to specialized plugins, complete with functional code examples.

Regex-Driven Validation Attached to jQuery Events

This method first strips every non-digit character from the input. Then, it runs a compact regular expression that checks for a country code and the correct length. This cleanup process keeps the pattern readable and fast.

You can chain the validation to "keyup" or "blur" events to give the user immediate feedback. The same handler can also query the element's "validity" property if you add an HTML "pattern" attribute. This provides a native user experience, as detailed on the MDN Web Docs. A Stack Overflow discussion offers more context.

const rx = /^1?\d{10}$/;          // “1” optional US CC + 10 digits
$("#phone").on("blur keyup", function () {
    const raw = $(this).val().trim().replace(/\D/g, "");
    const ok  = rx.test(raw);
    $(this).toggleClass("is-invalid", !ok);
});

The jQuery Validation Plugin

The popular jQuery Validation Plugin comes with a "phoneUS" rule available in its "additional-methods.js" file. You can also register custom rules for other regions with the "addMethod" function.

Validation with this plugin is declarative. The plugin also normalizes optional fields automatically and adds the necessary ARIA markup for accessibility, as shown in the official documentation.

$("#form").validate({
    rules: {
        phone: { required: true, phoneUS: true }    // built-in rule
    },
    messages: {
        phone: "10-digit US number required"
    }
});

The intl-tel-input Plugin

This plugin, a jQuery wrapper for "libphonenumber-JS", renders a country picker and formats the number as the user types. It uses the "isValidNumber()" or "isValidNumberPrecise()" functions for validation.

You can see validation examples on the plugin's website. Because numbering plans change often, only length-based validation is consistently safe for production environments.

const iti = $("#phone").intlTelInput({
    initialCountry: "auto",
    utilsScript: "/intl-tel-input/js/utils.js"
});
$("#btn").on("click", () => {
    if (iti.isValidNumber()) submitForm();
    else  showError(iti.getValidationError());
});

Challenges of jQuery Phone Number Validation

Standard jQuery validation methods appear simple but conceal significant flaws. These approaches often fail to handle the complexity of global numbering plans, which leads to inaccurate results and a poor user experience.

• A single regular expression fails to account for over 200 national plans. Lengths, optional prefixes, and varied separators cause pattern-based validation in jQuery to misfire, as users paste numbers in many formats.
• Dial rules often depend on location or network type. A front-end script, like one that uses the jQuery Validation Plugin, lacks the context to make an accurate yes-or-no decision, which makes validation a guess.
• Numbering plan data becomes outdated quickly. Plugins like intl-tel-input rely on metadata that needs constant updates to stay accurate. Without frequent redeploys, the validation logic drifts and produces false results for new or changed numbers.
• Client-side code only checks syntax, not if a number actually works. Methods that use regex or plugins like intl-tel-input approve numbers that look valid but may be disconnected. This limitation leads to false positives and missed edge cases.