Mastering Phone Number Formatting in JavaScript: Best Practices and Techniques

Phone numbers are a ubiquitous part of our daily lives. They are used for personal and professional communication, as well as for security and verification purposes. However, formatting phone numbers in JavaScript can be a challenging task. In this blog, we will explore the different techniques for formatting phone numbers in JavaScript and highlight some best practices for improving the user experience.

Basic Phone Number Formatting

Formatting a phone number can be achieved using regular expressions. A regular expression is a pattern that matches a string of text. For example, to format a phone number with the US country code (1) in the format (XXX) XXX-XXXX, we can use the following regular expression:

const phoneNumber = '1234567890';
const formattedPhoneNumber = phoneNumber.replace(/(\d{3})(\d{3})(\d{4})/, '($1) $2-$3');
console.log(formattedPhoneNumber);
// Output: (123) 456-7890

In the above code, we use the replace() method to replace the digits in the phone number with the desired format. The regular expression (\d{3})(\d{3})(\d{4}) matches three digits, followed by three digits, followed by four digits, and captures each group using parentheses. The replace string ($1) $2-$3 uses the captured groups to format the phone number.

Advanced Phone Number Formatting

Formatting phone numbers becomes more challenging when dealing with international phone numbers. International phone numbers can have different formats and different country codes. Fortunately, there are libraries available that can handle international phone number formatting.

One such library is Google's libphonenumber. Libphonenumber is a library for parsing, formatting, and validating phone numbers. It supports phone number formatting for over 200 countries and regions.

To use libphonenumber, we first need to install it using npm:

npm install google-libphonenumber

Then, we can use the parse() and format() methods to parse and format phone numbers:

const PNF = require('google-libphonenumber').PhoneNumberFormat;
const phoneUtil = require('google-libphonenumber').PhoneNumberUtil.getInstance();

const phoneNumber = '+14155552671';
const parsedPhoneNumber = phoneUtil.parse(phoneNumber);
const formattedPhoneNumber = phoneUtil.format(parsedPhoneNumber, PNF.INTERNATIONAL);
console.log(formattedPhoneNumber);
// Output: +1 415-555-2671

In the above code, we first import the PhoneNumberUtil class from libphonenumber. We then parse the phone number using the parse() method and format it using the format() method. The PhoneNumberFormat.INTERNATIONAL argument specifies that we want to format the phone number in international format.

Phone Number Input Masking

Input masking is a technique used to improve the user experience when entering data into a form. It involves formatting the input field as the user types. Input masking can be used for phone numbers to format them as the user types, making it easier for the user to enter the correct format.

One library that can be used for input masking is Inputmask.js. Inputmask.js is a lightweight and easy-to-use library for input masking. To use Inputmask.js, we first need to install it using npm:

npm install inputmask

Then, we can use the Inputmask() function to create an input mask for the phone number field:

const inputElement = document.getElementById('phone-number');
const maskOptions = {
  mask: '(999) 999-9999',
};
const inputMask = new Inputmask(maskOptions);
inputMask.mask(inputElement);

In the above code, we first select the phone number input field using the getElementById() method. We then create a mask options object with the desired mask format. Finally, we create an input mask using the Inputmask() function and apply it to the phone number input field using the mask() method.

User Experience Considerations

When formatting phone numbers, it is essential to consider the user experience. Formatting phone numbers can have an impact on the user experience, and it is important to ensure that the user can easily enter their phone number in the correct format.

One common issue with phone number formatting is the lack of flexibility in the input format. For example, if a form only allows phone numbers to be entered in a specific format, it may not accommodate different phone number formats used in different countries. To address this issue, it is recommended to use a flexible input format that can accommodate different phone number formats.

Another common issue with phone number formatting is the lack of validation. It is essential to validate phone numbers to ensure that they are entered correctly. Validation can be performed using regular expressions or libraries such as libphonenumber.

It is also important to consider accessibility when formatting phone numbers. Accessibility guidelines recommend that form fields should be labeled and described in a way that is understandable to all users, including those using assistive technologies.

Conclusion

Formatting phone numbers in JavaScript can be a challenging task. However, by using regular expressions, libraries such as libphonenumber, and input masking techniques, we can improve the user experience and ensure that phone numbers are entered in the correct format.

When formatting phone numbers, it is important to consider the user experience, including flexibility, validation, and accessibility. By following best practices and testing phone number formatting for usability and accessibility, we can ensure that our web applications are accessible to all users, regardless of their location or ability.

In conclusion, formatting phone numbers is an important aspect of web development, and it is essential to ensure that phone numbers are formatted correctly to improve the user experience and enhance the security and verification of our web applications.