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TypeScript is a superset of JavaScript that compiles to clean JavaScript output.
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sheetalkamat Merge pull request #33380 from microsoft/isolatedModules
With --isolatedModules, --declaration emit is now allowed and builder handles it for incremental compilation
Latest commit 7f004ad Sep 20, 2019
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.github Update (#32974) Aug 19, 2019
.vscode Fix ESLint extension config (#33501) Sep 19, 2019
bin Moved LKG folder to lib Jul 27, 2015
doc fix spelling errors Jan 28, 2019
lib Do not include built/local/enu when producing LKG (#32723) Aug 5, 2019
loc/lcl LEGO: check in for master to temporary branch. Sep 10, 2019
scripts remove .eslintrc from scripts Aug 20, 2019
src Merge pull request #33380 from microsoft/isolatedModules Sep 19, 2019
tests Merge pull request #33380 from microsoft/isolatedModules Sep 19, 2019
.dockerignore Add dockerfile based tests for `azure-sdk-for-js` and `office-ui-fabr… Jun 20, 2019
.editorconfig Use CRLF, not LF. Mar 2, 2015
.eslintignore exclude *.generated.d.ts files Jun 14, 2019
.eslintrc.json @typescript-eslint/quotes Aug 20, 2019
.gitattributes Never normalize end-of-lines on clone/commit. May 31, 2015
.gitignore Remove all submodules - just force clone and reset on run instead (#3… Sep 13, 2019
.gitmodules Remove all submodules - just force clone and reset on run instead (#3… Sep 13, 2019
.mailmap Update .mailmap Oct 27, 2018
.npmignore move eslint rules from eslint-plugin-microsoft-typescript to scripts/… Jul 24, 2019
.npmrc Remove lockfile, add to gitignore, and add npmrc preventing its gener… Aug 17, 2018
.travis.yml remove tslint, tslint:disable-next-line, update @typescript-eslint/* Jul 18, 2019
.yarnrc Adds a yarnrc which makes sure that the lockfile isn't generated for … Jun 12, 2019 Update authors for release 3.0 Jul 11, 2018 Added Microsoft code of conduct file Oct 5, 2018 Update docs to reflect the removal of the "Community" milestone. Apr 22, 2019
CopyrightNotice.txt Baseline public API (#18897) Oct 3, 2017
Dockerfile Add dockerfile based tests for `azure-sdk-for-js` and `office-ui-fabr… Jun 20, 2019
Gulpfile.js remove .eslintrc from scripts Aug 20, 2019
LICENSE.txt Add snapshot of compiler sources Jul 13, 2014 Merge branch 'master' of into… Aug 17, 2019
ThirdPartyNoticeText.txt Update ThirdPartyNoticeText to include KhronosGroup copyright notice … Jul 31, 2018
package.json Add build-eslint-rules to npm prepare script (#33417) Sep 13, 2019


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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 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

Change to the TypeScript directory:

cd TypeScript

Install Gulp tools and dev dependencies:

npm install -g gulp
npm install

Use one of the following to build and test:

gulp local             # Build the compiler into built/local.
gulp clean             # Delete the built compiler.
gulp LKG               # Replace the last known good with the built one.
                       # Bootstrapping step to be executed when the built compiler reaches a stable state.
gulp tests             # Build the test infrastructure using the built compiler.
gulp runtests          # Run tests using the built compiler and test infrastructure.
                       # Some low-value tests are skipped when not on a CI machine - you can use the
                       # --skipPercent=0 command to override this behavior and run all tests locally.
                       # You can override the specific suite runner used or specify a test for this command.
                       # Use --tests=<testPath> for a specific test and/or --runner=<runnerName> for a specific suite.
                       # Valid runners include conformance, compiler, fourslash, project, user, and docker
                       # The user and docker runners are extended test suite runners - the user runner
                       # works on disk in the tests/cases/user directory, while the docker runner works in containers.
                       # You'll need to have the docker executable in your system path for the docker runner to work.
gulp runtests-parallel # Like runtests, but split across multiple threads. Uses a number of threads equal to the system
                       # core count by default. Use --workers=<number> to adjust this.
gulp baseline-accept   # This replaces the baseline test results with the results obtained from gulp runtests.
gulp lint              # Runs eslint on the TypeScript source.
gulp 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.

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