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TypeScript: JavaScript With Syntax For Types.

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# TypeScript is **JavaScript with syntax for types.**

TypeScript is a strongly typed programming language that builds on JavaScript, giving you better tooling at any scale.

Try TypeScript Now

Online or via npm

- Editor Checks
- Auto-complete
- Interfaces
- JSX

ts

`const user = {    firstName: "Angela",    lastName: "Davis",    role: "Professor",  }  console.log(user.name)  Property 'name' does not exist on type '{ firstName: string; lastName: string; role: string; }'.2339Property 'name' does not exist on type '{ firstName: string; lastName: string; role: string; }'.`

ts

`const user = {    firstName: "Angela",    lastName: "Davis",    role: "Professor",  }  console.log(user.name)  Property 'name' does not exist on type '{ firstName: string; lastName: string; role: string; }'.2339Property 'name' does not exist on type '{ firstName: string; lastName: string; role: string; }'.`

TypeScript 5.9 is now available

## What is TypeScript?

### JavaScript and More

TypeScript adds additional syntax to JavaScript to support a **tighter integration with your editor**. Catch errors early in your editor.

### A Result You Can Trust

TypeScript code converts to JavaScript, which **runs anywhere JavaScript runs**: In a browser, on Node.js, Deno, Bun and in your apps.

### Safety at Scale

TypeScript understands JavaScript and uses **type inference to give you great tooling** without additional code.

## Get Started

Handbook

Learn the language

Playground

Try in your browser

Download

Install TypeScript

## Adopt TypeScript Gradually

Apply types to your JavaScript project incrementally, **each step improves editor support** and improves your codebase.

Let's take this incorrect JavaScript code, and see how **TypeScript can catch mistakes in your editor**.

js

`   function compact(arr) {      if (orr.length > 10)          return arr.trim(0, 10)      return arr  }   `

No editor warnings in JavaScript files

This code crashes at runtime!

JavaScript file

js

`   // @ts-check  function compact(arr) {    if (orr.length > 10)  Cannot find name 'orr'.2304Cannot find name 'orr'.      return arr.trim(0, 10)    return arr  }   `

Adding this to a JS file shows errors in your editor

the param is arr, not orr!

JavaScript with TS Check

js

`   // @ts-check  /** @param {any[]} arr */  function compact(arr) {      if (arr.length > 10)        return arr.trim(0, 10)  Property 'trim' does not exist on type 'any[]'.2339Property 'trim' does not exist on type 'any[]'.      return arr    }   `

Using JSDoc to give type information

Now TS has found a bad call. Arrays have slice, not trim.

JavaScript with JSDoc

ts

`   function compact(arr: string[]) {    if (arr.length > 10)      return arr.slice(0, 10)    return arr  }   `

TypeScript adds natural syntax for providing types

TypeScript file

### Describe Your Data

**Describe the shape of objects and functions** in your code.

Making it possible to see **documentation and issues in your editor**.

ts

`   interface Account {    id: number    displayName: string    version: 1  }  function welcome(user: Account) {    console.log(user.id)  }   `

ts

`   type Result = "pass" | "fail"  function verify(result: Result) {    if (result === "pass") {      console.log("Passed")    } else {      console.log("Failed")    }  }   `

## TypeScript becomes JavaScript via the delete key.

ts

`type Result = "pass" | "fail"  function verify(result: Result) {    if (result === "pass") {      console.log("Passed")    } else {      console.log("Failed")    }  }`

**TypeScript file**.

ts

`type Result = "pass" | "fail"  function verify(result: Result) {    if (result === "pass") {      console.log("Passed")    } else {      console.log("Failed")    }  }`

**Types are removed**.

js

`function verify(result) {    if (result === "pass") {      console.log("Passed")    } else {      console.log("Failed")    }  }`

**JavaScript file**.

## TypeScript Testimonials

**First**, we were surprised by the number of small bugs we found when converting our code.

**Second**, we underestimated how powerful the editor integration is.

TypeScript was such a boon to our stability and sanity that we started using it for all new code within days of starting the conversion.

Felix Rieseberg at Slack covered the transition of their desktop app from JavaScript to TypeScript in their blog

Read

### Open Source with TypeScript

Angular

Vue

Jest

Redux

Ionic

Probot

Deno

Vercel

Yarn

GitHub
Desktop

## Loved by Developers

Voted **2nd most loved programming language** in the Stack Overflow 2020 Developer survey

TypeScript was **used by 78%** of the 2020 State of JS respondents, with **93% saying they would use it again**.

TypeScript was given the award for **“Most Adopted Technology”** based on year-on-year growth.

## Get Started

Handbook

Learn the language

Playground

Try in your browser

Download

Install TypeScript

Made with ♥ in Redmond, Boston, SF & Dublin

© 2012-2025 Microsoft
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### Using TypeScript

- Get Started
- Download
- Community
- Playground
- TSConfig Ref
- Code Samples
- Why TypeScript
- Design

### Community

- Get Help
- Blog
- GitHub Repo
- Community Chat
- @TypeScript
- Mastodon
- Stack Overflow
- Web Repo

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