TypeScript is a superset of JavaScript that compiles to clean JavaScript output.
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.github Update bug template to version 3.3 Nov 20, 2018
.vscode Migrate tscWatchMode to vfs Nov 22, 2017
bin Moved LKG folder to lib Jul 27, 2015
doc Update spec.md Oct 2, 2018
lib Update LKG. Nov 20, 2018
scripts Fix gulp baseline-accept (#29301) Jan 8, 2019
src Add opt-in user preference for prefix and suffix text on renames (#29314 Jan 16, 2019
tests Update user baselines (#29444) Jan 16, 2019
.editorconfig Use CRLF, not LF. Mar 2, 2015
.gitattributes Never normalize end-of-lines on clone/commit. May 31, 2015
.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
.npmrc Remove lockfile, add to gitignore, and add npmrc preventing its gener… Aug 17, 2018
.travis.yml Adjust travis branch spec to capture all release branches (#29086) Dec 18, 2018
AUTHORS.md Update authors for release 3.0 Jul 11, 2018
CODE_OF_CONDUCT.md Added Microsoft code of conduct file Oct 5, 2018
CopyrightNotice.txt Baseline public API (#18897) Oct 3, 2017
Gulpfile.js Always generate lowercase locale names so 'LKG's produce identical re… Dec 10, 2018
Jakefile.js Always generate lowercase locale names so 'LKG's produce identical re… Dec 10, 2018
LICENSE.txt Add snapshot of compiler sources Jul 13, 2014
README.md Fix broken twitter link in README Oct 31, 2018
ThirdPartyNoticeText.txt Update ThirdPartyNoticeText to include KhronosGroup copyright notice … Jul 31, 2018
completionAtDottedNamespace.ts Verify that completion with new identifier location returns isNewIden… Jan 9, 2019
package.json Build - List "pretty-hrtime" as a dev dependency in root "package.json". Dec 13, 2018
tslint.json Enable '--strictNullChecks' (#22088) May 22, 2018


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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.