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TypeScript is a language for application scale JavaScript development


TypeScript is a language for application-scale JavaScript. TypeScript adds optional types, classes, and modules to JavaScript. TypeScript supports tools for large-scale JavaScript applications for any browser, for any host, on any OS. TypeScript compiles to readable, standards-based JavaScript. Try it out at the playground, and stay up to date via our blog and Twitter account.

For the latest stable version:

npm install -g typescript

For our nightly builds:

npm install -g typescript@next

There are many ways to contribute to TypeScript.

In order to build the TypeScript compiler, ensure that you have Git and Node.js installed.

Clone a copy of the repo:

git clone

Change to the TypeScript directory:

cd TypeScript

Install Jake tools and dev dependencies:

npm install -g jake
npm install

Use one of the following to build and test:

jake local            # Build the compiler into built/local 
jake clean            # Delete the built compiler 
jake LKG              # Replace the last known good with the built one.
                      # Bootstrapping step to be executed when the built compiler reaches a stable state.
jake tests            # Build the test infrastructure using the built compiler. 
jake runtests         # Run tests using the built compiler and test infrastructure. 
                      # You can override the host or specify a test for this command. 
                      # Use host=<hostName> or tests=<testPath>. 
jake runtests-browser # Runs the tests using the built run.js file. Syntax is jake runtests. Optional
                        parameters 'host=', 'tests=[regex], reporter=[list|spec|json|<more>]'.
jake baseline-accept  # This replaces the baseline test results with the results obtained from jake runtests.
jake lint             # Runs tslint on the TypeScript source.
jake -T               # List the above commands. 
node built/local/tsc.js hello.ts

For details on our planned features and future direction please refer to our roadmap.