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Previously, null/undefined were removed upfront, which is incorrect. Now nullable types are removed with other non-primitives after union is lifted over spread. This produces unions, which are larger, but more correct.
TypeScript
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.
Installing
For the latest stable version:
npm install -g typescript
For our nightly builds:
npm install -g typescript@next
Contribute
There are many ways to contribute to TypeScript.
- Submit bugs and help us verify fixes as they are checked in.
- Review the source code changes.
- Engage with other TypeScript users and developers on StackOverflow.
- Join the #typescript discussion on Twitter.
- Contribute bug fixes.
- Read the language specification (docx, pdf, md).
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.
Documentation
Building
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 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.
# You can override the host or specify a test for this command.
# Use host=<hostName> or tests=<testPath>.
gulp runtests-browser # Runs the tests using the built run.js file. Syntax is gulp runtests. Optional
parameters 'host=', 'tests=[regex], reporter=[list|spec|json|<more>]'.
gulp baseline-accept # This replaces the baseline test results with the results obtained from gulp runtests.
gulp lint # Runs tslint on the TypeScript source.
gulp help # List the above commands.
Usage
node built/local/tsc.js hello.ts
Roadmap
For details on our planned features and future direction please refer to our roadmap.