Discover How to Easily Format Phone Numbers with JavaScript – See Working Code Examples

Table of content

  1. Introduction
  2. Why is proper phone number formatting important?
  3. Basic format for US phone numbers
  4. Common JavaScript methods for formatting phone numbers
  5. Working code example: using regex to format phone numbers
  6. Bonus tip: international phone number formatting
  7. Conclusion


When it comes to formatting phone numbers in web applications, there is no one-size-fits-all solution. Different countries have different formats for phone numbers, and even within a single country, there may be variations depending on the region or the type of phone number (landline vs mobile). Fortunately, JavaScript provides a variety of tools that can help you easily format phone numbers to fit the requirements of your specific application. In this article, we will explore some of the most common techniques for formatting phone numbers using JavaScript, including regular expressions and third-party libraries. We will also provide working code examples that you can use in your own projects. Whether you are building a simple contact form or a complex phone directory application, this article will give you the tools you need to format phone numbers with ease.

Why is proper phone number formatting important?

Proper phone number formatting is important for several reasons. Firstly, it makes it easier to read and remember phone numbers, especially when they are long or contain special characters. This is particularly important for businesses that rely on clients being able to remember their phone number in order to contact them. In addition, standardized phone number formatting is essential for efficient data management, as it allows for accurate and consistent use of phone numbers across different platforms and systems. This is particularly important when dealing with large datasets, as inconsistencies in phone number formats can lead to errors and inaccurate analysis. Finally, proper phone number formatting is important for security reasons, as it helps prevent fraud and identity theft by ensuring that phone numbers are easily verified and authenticated. Overall, proper phone number formatting is important for ensuring that phone numbers are easy to read, remember, and manage, while also providing an important layer of security for businesses and individuals alike.

Basic format for US phone numbers

In the US, phone numbers typically follow a specific format that is commonly used across the country. To format a US phone number using JavaScript, the following format can be used:

function formatPhoneNumber(phoneNumberString) {
    var cleaned = phoneNumberString.replace(/\D/g, '');
    var match = cleaned.match(/^(\d{3})(\d{3})(\d{4})$/);
    if (match) {
        return '(' + match[1] + ') ' + match[2] + '-' + match[3];
    return null;

This function takes in a phone number string and outputs it in the format (xxx) xxx-xxxx. Here's how the function works:

  1. First, the function removes all non-numeric characters from the string using the replace() method and a regular expression. This ensures that the phone number only contains digits.
  2. Next, the function tries to match the cleaned string to a specific pattern using a regular expression.
  3. The regular expression ^(\d{3})(\d{3})(\d{4})$ matches a string that starts with three digits, then has another three digits, and ends with four digits.
  4. If the string matches this pattern, the function returns the properly formatted phone number string by concatenating the matched groups with the desired characters.

This format can be used as a starting point for formatting other types of phone numbers as well. By adjusting the regular expression to match the specific pattern of a different country's phone numbers, for instance, the function can be modified to format phone numbers from other parts of the world.

Common JavaScript methods for formatting phone numbers

There are several JavaScript methods you can use for formatting phone numbers. Here are a few common ones:

  • replace(): This method allows you to replace specific characters in a string with new characters. You can use it to add dashes, parentheses, or other formatting elements to a phone number string. For example:
let phoneNumber = "5551234567";
phoneNumber = phoneNumber.replace(/(\d{3})(\d{3})(\d{4})/, "($1) $2-$3");

This code would format the phoneNumber variable to look like "(555) 123-4567".

  • match(): This method searches a string for a specified pattern and returns an array containing the matches. You can use it to extract specific parts of a phone number string, such as the area code or the extension. For example:
let phoneNumber = "555-123-4567 ext. 1234";
let areaCode = phoneNumber.match(/\d{3}/g)[0];
let extension = phoneNumber.match(/ext. (\d+)/)[1];

This code would extract the area code as "555" and the extension as "1234".

  • slice(): This method returns a portion of a string starting from a specified index and ending at a specified index. You can use it to remove certain characters from a phone number string, such as spaces or dashes. For example:
let phoneNumber = "(555) 123-4567";
phoneNumber = phoneNumber.slice(1, 4) + phoneNumber.slice(6, 9) + phoneNumber.slice(10);

This code would remove the parentheses and dash from the phoneNumber variable, resulting in "5551234567".

Working code example: using regex to format phone numbers

Regular expressions, or regex, are a powerful tool for searching and manipulating text. In JavaScript, regex can be used to format phone numbers in various ways. Here's an example code snippet that formats a US phone number in the format (xxx) xxx-xxxx:

function formatPhoneNumber(phoneNumberString) {
  // Remove all non-digit characters
  const cleaned = ('' + phoneNumberString).replace(/\D/g, '');
  // Capture the first 3 digits and surround them with parentheses
  const match = cleaned.match(/^(\d{3})(\d{0,3})(\d{0,4})$/);
  // Assemble the formatted phone number
  const formatted = '(' + match[1] + ') ' + match[2] + '-' + match[3];
  return formatted;

console.log(formatPhoneNumber('123-456-7890')); // Returns "(123) 456-7890"
console.log(formatPhoneNumber('5551234')); // Returns "(555) 123-4"

Let's break down how this function works:

  1. cleaned = ('' + phoneNumberString).replace(/\D/g, '');

    This line removes all non-digit characters from the input phoneNumberString. The /\D/g regex matches any character that is not a digit (\D) globally (g) in the string. The resulting cleaned variable will only contain digits.

  2. const match = cleaned.match(/^(\d{3})(\d{0,3})(\d{0,4})$/);

    This line uses regex to capture the three groups of digits that make up a phone number: the area code (3 digits), prefix (up to 3 digits), and line number (up to 4 digits). The ^ and $ symbols anchor the regex to the start and end of the string, ensuring that the entire input is matched. The (\d{3}), (\d{0,3}), and (\d{0,4}) capture groups match the corresponding number of digits in the input string. These capture groups are stored in the match array.

  3. const formatted = '(' + match[1] + ') ' + match[2] + '-' + match[3];

    This line assembles the formatted phone number using the captured digit groups. The parentheses around the area code are added manually, while the prefix and line number are concatenated with hyphens. The resulting formatted variable contains the complete, formatted phone number.

This code example is just one of many ways to format phone numbers using regex in JavaScript. By understanding the basics of regex, you can easily adapt this code to fit your specific phone number formatting requirements.

Bonus tip: international phone number formatting

Formatting phone numbers in different countries can be a challenge. Each country has its own format for phone numbers, with different numbers of digits, separators, and other rules. Here are some examples of international phone number formats:

  • Germany: +49 1234 567890
  • Japan: +81 3 1234 5678
  • Brazil: +55 (11) 1234-5678
  • India: +91 12345 67890

To handle all these formats, you can use a JavaScript library such as Google's libphonenumber. This library provides a set of functions for parsing, formatting, and validating phone numbers in various countries. Here is an example of how to format a phone number using this library:

const phoneUtil = require('google-libphonenumber').PhoneNumberUtil.getInstance();
const number = phoneUtil.parseAndKeepRawInput('1234567890', 'US');
const formattedNumber = phoneUtil.format(number, PhoneNumberFormat.INTERNATIONAL);
console.log(formattedNumber); // +1 123-456-7890

In this example, we first create a PhoneNumber object by parsing a raw input string (1234567890) and specifying the country (US). Then, we use the format() function to format the phone number in international format (+1 123-456-7890).

Note that the parseAndKeepRawInput() function is used to preserve any formatting or other characters in the input string. This is useful for cases where the user may have entered the phone number in a non-standard format.

By using a library like libphonenumber, you can ensure that your application handles phone numbers correctly for users in different countries, improving the user experience and reducing errors.


In , formatting phone numbers in JavaScript is a useful skill to have in web development. With the examples provided in this article, you can see how easy it is to use regular expressions and built-in JavaScript methods to format phone numbers according to your needs. Whether you want to add parentheses, hyphens, or any other formatting, the code examples in this article should help you achieve your goal.

Formatting phone numbers not only creates a more aesthetically pleasing appearance but also increases usability for users. By making phone numbers easily recognizable and readable, users are more likely to input the correct information without errors.

Additionally, formatting phone numbers is just one example of how JavaScript can be used to manipulate and validate user input. With JavaScript, you can create dynamic websites that respond to user input in real-time, making for a more engaging user experience.

We hope this article has been helpful in showing you how to format phone numbers in JavaScript. As you continue your web development journey, we encourage you to experiment with different formats and methods to make your websites even more user-friendly.

As a developer, I have experience in full-stack web application development, and I'm passionate about utilizing innovative design strategies and cutting-edge technologies to develop distributed web applications and services. My areas of interest extend to IoT, Blockchain, Cloud, and Virtualization technologies, and I have a proficiency in building efficient Cloud Native Big Data applications. Throughout my academic projects and industry experiences, I have worked with various programming languages such as Go, Python, Ruby, and Elixir/Erlang. My diverse skillset allows me to approach problems from different angles and implement effective solutions. Above all, I value the opportunity to learn and grow in a dynamic environment. I believe that the eagerness to learn is crucial in developing oneself, and I strive to work with the best in order to bring out the best in myself.
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