What Inputmask Does

Inputmask is a JavaScript tool that formats user input as people type into form fields. Instead of letting users enter data however they want, it gently enforces a specific structure—like automatically inserting dashes in a phone number, or preventing letters where only numbers make sense. The benefit is cleaner data going into your system and a better experience for users who don't have to guess the right format.

How It Works

The library watches what a user types and compares it against a pattern you define. Patterns use simple symbols: "9" means a digit, "a" means a letter, and so on. For example, the pattern "(999) 999-9999" creates a phone number field that automatically formats input into that shape. The tool can run in different environments—on plain HTML pages using a script tag, in frameworks like jQuery, or in modern JavaScript bundlers like webpack. It can also read formatting rules directly from HTML attributes, so you can add a phone number field without writing any JavaScript.

Who Uses It

Anyone building a web form that collects structured data can benefit. Common use cases include phone numbers, dates, credit card numbers, postal codes, currency amounts, and email addresses. A founder building a SaaS product might use it to make signup forms feel polished. A PM improving a checkout flow could use it to reduce form abandonment from confused users. A freelancer or small business building simple web tools would appreciate how easy it is to drop in and configure.

Notable Features

The library offers quite a bit of flexibility. You can define optional parts of a mask (like an optional extension on a phone number), create dynamic masks that expand as needed, or set up multiple mask options for users to choose between. You can also write custom validation rules, handle edge cases like right-to-left languages, and even validate or format data without an actual input field. It's been around since 2010 and works across browsers, which means it's stable and battle-tested.