About TypeScript
TypeScript is an open source language that adds static types to JavaScript. Your editor and compiler use those types to catch mistakes before the code runs.
What it does
TypeScript adds type annotations and type inference on top of JavaScript syntax. The compiler checks your code and removes the type syntax when it outputs plain JavaScript, which then runs in browsers, Node.js, Deno, Bun or any other JavaScript environment. Editors use the same information to offer completion, navigation and inline error messages.
Key features
- Type checks that run before the code runs
- Autocomplete and error messages in editors
- Gradual adoption in existing JavaScript files
- JSDoc comments can carry type information
- Output is plain JavaScript that runs anywhere
Who it's for
JavaScript teams that work on large or long-lived codebases, and developers who want safer refactoring. It also suits anyone who wants clearer contracts between the parts of an app.
Pricing and good to know
TypeScript is free and open source, with its code on GitHub under the Apache 2.0 license. You can try it in an online playground or install it through npm. Types add a build step and some setup, and the compiler can be strict, so expect some time spent on configuration.
Highlights
- Type checks that run before your code runs
- Autocomplete and inline errors in your editor
- Gradual adoption inside existing JavaScript files
- Types written in JSDoc comments for plain JS
- Compiles to plain JavaScript that runs anywhere
