TypeScript is a superset of JavaScript that compiles to clean JavaScript output.
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bin Moved LKG folder to lib Jul 27, 2015
doc Fix typo in Array Type Literals section of spec Mar 28, 2018
lib Update LKG and remove newly unnecessary non-null assertions (#26515) Aug 17, 2018
scripts Fix overlapping test runs in 'gulp watch' Aug 29, 2018
src Merge pull request #22776 from amcasey/GH22607 Sep 19, 2018
tests Merge pull request #22776 from amcasey/GH22607 Sep 19, 2018
.editorconfig Use CRLF, not LF. Mar 2, 2015
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.gitignore Remove lockfile, add to gitignore, and add npmrc preventing its gener… Aug 17, 2018
.gitmodules Add prettier user test and fix associated crash (#23715) Apr 26, 2018
.mailmap Update authors for release 3.0.1 Jul 27, 2018
.npmignore Add `.mailmap` and `Test-results.xml` to .npmignore Jul 24, 2018
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.travis.yml Add release-3.0 to supported branches Jul 11, 2018
AUTHORS.md Update authors for release 3.0 Jul 11, 2018
CopyrightNotice.txt Baseline public API (#18897) Oct 3, 2017
Gulpfile.js Fix overlapping test runs in 'gulp watch' Aug 29, 2018
Jakefile.js Hardcode xunit reporter output file into failed tests reporter Aug 6, 2018
LICENSE.txt Add snapshot of compiler sources Jul 13, 2014
README.md Update README.md: JavaScript has modules and classes Aug 3, 2018
ThirdPartyNoticeText.txt Update ThirdPartyNoticeText to include KhronosGroup copyright notice … Jul 31, 2018
package.json Add codefix to generate types for untyped module (#26588) Sep 18, 2018
tslint.json Enable '--strictNullChecks' (#22088) May 22, 2018


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Join the chat at https://gitter.im/Microsoft/TypeScript

TypeScript is a language for application-scale JavaScript. TypeScript adds optional types to JavaScript that support 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.

This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact opencode@microsoft.com with any additional questions or comments.



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

Clone a copy of the repo:

git clone https://github.com/Microsoft/TypeScript.git

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 help             # 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.