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Bazel rules for TypeScript

This is the canonical ruleset for using Bazel with TypeScript, based on https://github.com/aspect-build/rules_js.

Many companies are successfully building with rules_ts. If you're getting value from the project, please let us know! Just comment on our Adoption Discussion.

This is a high-performance alternative to the @bazel/typescript npm package from rules_nodejs. The ts_project rule here is identical to the one in rules_nodejs, making it easy to migrate. Since rules_js always runs tools from the bazel-out tree, rules_ts naturally fixes most usability bugs with rules_nodejs:

• Freely mix generated *.ts and tsconfig.json files in the bazel-out tree with source files
• Fixes the need for any rootDirs settings in tsconfig.json as reported in https://github.com/microsoft/TypeScript/issues/37378
• "worker mode" for ts_project now shares workers across all targets, rather than requiring one worker pool per target

rules_ts is just a part of what Aspect provides:

• Need help? This ruleset has support provided by https://www.aspect.dev/bazel-open-source-support.
• See our other Bazel rules, especially those built for rules_js, linked from https://github.com/aspect-build

Known issues:

• Type-checking can not be performed in parallel, see --isolatedDeclarations

Installation

Follow instructions from the release you wish to use: https://github.com/aspect-build/rules_ts/releases

Examples

There are a number of examples in the examples/ folder and larger examples in the bazel-examples repository using rules_ts such as jest, react, angular.

If you'd like an example added, you can fund a Feature Request.

Usage

See the API documentation in the docs/ folder.

From a BUILD file

The most common use is with the ts_project macro which invokes a transpiler you configure to transform source files like .ts files into outputs such as .js and .js.map, and the tsc CLI to type-check the program and produce .d.ts files.

In a macro

Many organizations set default values, so it's common to write a macro to wrap ts_project, then ensure that your developers load your macro rather than loading from @aspect_rules_ts directly.

BUILD file generation

Aspect provides a TypeScript BUILD file generator as part of the Aspect CLI. Run aspect configure to create or update BUILD.bazel files as you edit TypeScript sources. See https://docs.aspect.build/cli/commands/aspect_configure.

Advanced: custom rules

If you know how to write Bazel rules, you might find that ts_project doesn't do what you want.

One way to customize it is to peel off one layer of indirection, by calling the ts_project_rule directly. This bypasses our default setting logic, and also the validation program which checks that ts_project attributes are well-formed.

You can also write a custom rule from scratch. We expose helper functions from /ts/private in this repo. Be aware that these are not a public API, so you may have to account for breaking changes which aren't subject to our usual semver policy.