This contains references to the symbols we want documented.

We can't point stardoc to the top-level index.bzl since then it will see macros rather than the rules they wrap. So this is a copy of index.bzl with macro indirection removed.



Allows a tsconfig.json file to extend another file.

Normally, you just give a single tsconfig.json file as the tsconfig attribute of a ts_library or ts_project rule. However, if your tsconfig.json uses the extends feature from TypeScript, then the Bazel implementation needs to know about that extended configuration file as well, to pass them both to the TypeScript compiler.


A unique name for this target.


Additional tsconfig.json files referenced via extends


The tsconfig.json file passed to the TypeScript compiler


ts_devserver is a simple development server intended for a quick "getting started" experience.

Additional documentation here


A unique name for this target.


Additional root paths to serve static_files from. Paths should include the workspace name such as ["__main__/resources"]


Scripts to include in the JS bundle before the module loader (require.js)


Targets that produce JavaScript, such as ts_library


Go based devserver executable.

With cross-platform RBE for OSX & Windows ctx.executable.devserver will be linux as --cpu and --host_cpu must be overridden to k8. However, we still want to be able to run the devserver on the host machine so we need to include the host devserver binary, which is ctx.executable.devserver_host, in the runfiles. For non-RBE and for RBE with a linux host, ctx.executable.devserver & ctx.executable.devserver_host will be the same binary.

Defaults to precompiled go binary setup by @bazel/typescript npm package


Go based devserver executable for the host platform. Defaults to precompiled go binary setup by @bazel/typescript npm package


The entry_module should be the AMD module name of the entry module such as "__main__/src/index". ts_devserver concats the following snippet after the bundle to load the application: require(["entry_module"]);


The port that the devserver will listen on.


User scripts to include in the JS bundle before the application sources


The path you can request from the client HTML which serves the JavaScript bundle. If you don't specify one, the JavaScript can be loaded at /_/ts_scripts.js


Arbitrary files which to be served, such as index.html. They are served relative to the package where this rule is declared.


ts_library type-checks and compiles a set of TypeScript sources to JavaScript.

First read the Alternatives section above. ts_project is recommended for new uses.

The ts_library rule invokes the TypeScript compiler on one compilation unit, or "library" (generally one directory of source files). It produces declarations files (.d.ts) which are used for compiling downstream TypeScript targets and JavaScript for the browser and Closure compiler.

To start, create a BUILD file next to your sources:

load("@npm//@bazel/typescript:index.bzl", "ts_library")

    name = "my_code",
    srcs = glob(["*.ts"]),
    deps = ["//path/to/other:library"],

If your ts_library target has npm dependencies you can specify these with fine grained npm dependency targets created by the yarn_install or npm_install rules:

    name = "my_code",
    srcs = glob(["*.ts"]),
    deps = [

You can also use the @npm//@types target which will include all packages in the @types scope as dependencies.

If you are using self-managed npm dependencies, you can use the node_modules attribute in ts_library and point it to the //:node_modules filegroup defined in your root BUILD.bazel file. You'll also need to override the compiler attribute if you do this as the Bazel-managed deps and self-managed cannot be used together in the same rule.

    name = "my_code",
    srcs = glob(["*.ts"]),
    deps = ["//path/to/other:library"],
    node_modules = "//:node_modules",
    compiler = "//:@bazel/typescript/tsc_wrapped",

To build a ts_library target run:

bazel build //path/to/package:target

The resulting .d.ts file paths will be printed. Additionally, the .js outputs from TypeScript will be written to disk, next to the .d.ts files 1.

Note that the tsconfig.json file used for compilation should be the same one your editor references, to keep consistent settings for the TypeScript compiler. By default, ts_library uses the tsconfig.json file in the workspace root directory. See the notes about the tsconfig attribute in the ts_library API docs.

1 The declarationDir compiler option will be silently overwritten if present.

Self-managed npm dependencies

We recommend you use Bazel managed dependencies, but if you would like Bazel to also install a node_modules in your workspace you can also point the node_repositories repository rule in your WORKSPACE file to your package.json.

node_repositories(package_json = ["//:package.json"])

You can then run yarn in your workspace with:

$ bazel run @nodejs//:yarn_node_repositories

To use your workspace node_modules folder as a dependency in ts_library and other rules, add the following to your root BUILD.bazel file:

    name = "node_modules",
    srcs = glob(
        include = [
        exclude = [
          # Files under test & docs may contain file names that
          # are not legal Bazel labels (e.g.,
          # node_modules/ecstatic/test/public/中文/檔案.html)
          # Files with spaces in the name are not legal Bazel labels
          "node_modules/**/* */**",
          "node_modules/**/* *",

# Create a tsc_wrapped compiler rule to use in the ts_library
# compiler attribute when using self-managed dependencies
    name = "@bazel/typescript/tsc_wrapped",
    entry_point = "@npm//:node_modules/@bazel/typescript/internal/tsc_wrapped/tsc_wrapped.js",
    # Point bazel to your node_modules to find the entry point
    node_modules = "//:node_modules",

See for more information on managing npm dependencies with Bazel.

Customizing the TypeScript compiler binary

An example use case is needing to increase the NodeJS heap size used for compilations.

Similar to above, you declare your own binary for running tsc_wrapped, e.g.:

    name = "tsc_wrapped_bin",
    entry_point = "@npm//:node_modules/@bazel/typescript/internal/tsc_wrapped/tsc_wrapped.js",
    templated_args = [
    data = [

then refer to that target in the compiler attribute of your ts_library rule.

Note that nodejs_binary targets generated by npm_install/yarn_install can include data dependencies on packages which aren't declared as dependencies. For example, if you use tsickle to generate Closure Compiler-compatible JS, then it needs to be a data dependency of tsc_wrapped so that it can be loaded at runtime.

Accessing JavaScript outputs

The default output of the ts_library rule is the .d.ts files. This is for a couple reasons:

  • help ensure that downstream rules which access default outputs will not require a cascading re-build when only the implementation changes but not the types
  • make you think about whether you want the devmode (named UMD) or prodmode outputs

You can access the JS output by adding a filegroup rule after the ts_library, for example

    name = "compile",
    srcs = ["thing.ts"],

    name = "thing.js",
    srcs = ["compile"],
    # Change to es6_sources to get the 'prodmode' JS
    output_group = "es5_sources",

    name = "uses_js",
    deps = ["thing.js"],

Serving TypeScript for development

There are two choices for development mode:

  1. Use the ts_devserver rule to bring up our simple, fast development server. This is intentionally very simple, to help you get started quickly. However, since there are many development servers available, we do not want to mirror their features in yet another server we maintain.
  2. Teach your real frontend server to serve files from Bazel's output directory. This is not yet documented. Choose this option if you have an existing server used in development mode, or if your requirements exceed what the ts_devserver supports. Be careful that your development round-trip stays fast (should be under two seconds).

To use ts_devserver, you simply load the rule, and call it with deps that point to your ts_library target(s):

load("@npm//@bazel/typescript:index.bzl", "ts_devserver", "ts_library")

    name = "app",
    srcs = ["app.ts"],

    name = "devserver",
    # We'll collect all the devmode JS sources from these TypeScript libraries
    deps = [":app"],
    # This is the path we'll request from the browser, see index.html
    serving_path = "/bundle.js",
    # The devserver can serve our static files too
    static_files = ["index.html"],

The index.html should be the same one you use for production, and it should load the JavaScript bundle from the path indicated in serving_path.

If you don't have an index.html file, a simple one will be generated by the ts_devserver.

See examples/app in this repository for a working example. To run the devserver, we recommend you use ibazel:

$ ibazel run examples/app:devserver

ibazel will keep the devserver program running, and provides a LiveReload server so the browser refreshes the application automatically when each build finishes.

Writing TypeScript code for ts_library

The custom TypeScript compiler tsc_wrapped has your workspace path mapped, so you can import from an absolute path starting from your workspace.


workspace(name = "myworkspace")


import {thing} from 'myworkspace/place';

will import from /place.ts.

Since this is an extension to the vanilla TypeScript compiler, editors which use the TypeScript language services to provide code completion and inline type checking will not be able to resolve the modules. In the above example, adding

"paths": {
    "myworkspace/*": ["*"]

to tsconfig.json will fix the imports for the common case of using absolute paths. See path mapping for more details on the paths syntax.

Similarly, you can use path mapping to teach the editor how to resolve imports from ts_library rules which set the module_name attribute.


A unique name for this target.


Additional files the Angular compiler will need to read as inputs. Includes .css and .html files


Sets a different TypeScript compiler binary to use for this library. For example, we use the vanilla TypeScript tsc.js for bootstrapping, and Angular compilations can replace this with ngc.

The default ts_library compiler depends on the //@bazel/typescript target which is setup for projects that use bazel managed npm deps and install the @bazel/typescript npm package.



Compile-time dependencies, typically other ts_library targets


Set the typescript module compiler option for devmode output.

This value will override the module option in the user supplied tsconfig.


Set the typescript target compiler option for devmode output.

This value will override the target option in the user supplied tsconfig.




Testing only, whether to type check inputs that aren't srcs.

Link the workspace root to the bin_dir to support absolute requires like 'my_wksp/path/to/file'. If source files need to be required then they can be copied to the bin_dir with copy_to_bin.




The npm packages which should be available during the compile.

The default value of //typescript:typescript__typings is setup for projects that use bazel managed npm deps. This default is in place since ts_library will always depend on at least the typescript default libs which are provided by //typescript:typescript__typings.

This attribute is DEPRECATED. As of version 0.18.0 the recommended approach to npm dependencies is to use fine grained npm dependencies which are setup with the yarn_install or npm_install rules.

For example, in targets that used a //:node_modules filegroup,

    name = "my_lib",
    node_modules = "//:node_modules",

which specifies all files within the //:node_modules filegroup to be inputs to the my_lib. Using fine grained npm dependencies, my_lib is defined with only the npm dependencies that are needed:

    name = "my_lib",
    deps = [

In this case, only the listed npm packages and their transitive deps are includes as inputs to the my_lib target which reduces the time required to setup the runfiles for this target (see The default typescript libs are also available via the node_modules default in this case.

The @npm external repository and the fine grained npm package targets are setup using the yarn_install or npm_install rule in your WORKSPACE file:

    name = "npm",
    package_json = "//:package.json",
    yarn_lock = "//:yarn.lock",


Set the typescript module compiler option for prodmode output.

This value will override the module option in the user supplied tsconfig.


Set the typescript target compiler option for prodmode output.

This value will override the target option in the user supplied tsconfig.




The TypeScript source files to compile.


Intended for internal use only.

Allows you to disable the Bazel Worker strategy for this library. Typically used together with the "compiler" setting when using a non-worker aware compiler binary.


A tsconfig.json file containing settings for TypeScript compilation. Note that some properties in the tsconfig are governed by Bazel and will be overridden, such as target and module.

The default value is set to //:tsconfig.json by a macro. To use the default, create a BUILD.bazel file in your workspace root. If your tsconfig.json file is in the root, use

exports_files(["tsconfig.json"], visibility = ["//visibility:public"])

otherwise create an alias:

    name = "tsconfig.json",
    actual = "//path/to/my:tsconfig.json",

Or, instead of the default you can give an explicit tsconfig attribute to all ts_library targets.


If using tsickle, instruct it to translate types to ClosureJS format


Run the Angular ngtsc compiler under ts_library

Macros and Functions


Compiles one TypeScript project using tsc --project

This is a drop-in replacement for the tsc rule automatically generated for the "typescript" package, typically loaded from @npm//typescript:index.bzl. Unlike bare tsc, this rule understands the Bazel interop mechanism (Providers) so that this rule works with others that produce or consume TypeScript typings (.d.ts files).

Unlike ts_library, this rule is the thinnest possible layer of Bazel interoperability on top of the TypeScript compiler. It shifts the burden of configuring TypeScript into the tsconfig.json file. See for more details about the trade-offs between the two rules.

Some TypeScript options affect which files are emitted, and Bazel wants to know these ahead-of-time. So several options from the tsconfig file must be mirrored as attributes to ts_project. See for a listing of the TypeScript options.

Any code that works with tsc should work with ts_project with a few caveats:

  • Bazel requires that the outDir (and declarationDir) be set to bazel-out/[target architecture]/bin/path/to/package so we override whatever settings appear in your tsconfig.
  • Bazel expects that each output is produced by a single rule. Thus if you have two ts_project rules with overlapping sources (the same .ts file appears in more than one) then you get an error about conflicting .js output files if you try to build both together. Worse, if you build them separately then the output directory will contain whichever one you happened to build most recently. This is highly discouraged.

Note: in order for TypeScript to resolve relative references to the bazel-out folder, we recommend that the base tsconfig contain a rootDirs section that includes all possible locations they may appear.

We hope this will not be needed in some future release of TypeScript. Follow for more info.

For example, if the base tsconfig file relative to the workspace root is path/to/tsconfig.json then you should configure like:

"compilerOptions": {
    "rootDirs": [

See some related discussion including both "rootDirs" and "paths" for a monorepo setup using custom import paths:

Issues when running non-sandboxed

When using a non-sandboxed spawn strategy (which is the default on Windows), you may observe these problems which require workarounds:

  1. Bazel deletes outputs from the previous execution before running tsc. This causes a problem with TypeScript's incremental mode: if the .tsbuildinfo file is not known to be an output of the rule, then Bazel will leave it in the output directory, and when tsc runs, it may see that the outputs written by the prior invocation are up-to-date and skip the emit of these files. This will cause Bazel to intermittently fail with an error that some outputs were not written. This is why we depend on composite and/or incremental attributes to be provided, so we can tell Bazel to expect a .tsbuildinfo output to ensure it is deleted before a subsequent compilation. At present, we don't do anything useful with the .tsbuildinfo output, and this rule does not actually have incremental behavior. Deleting the file is actually counter-productive in terms of TypeScript compile performance. Follow

  2. When using Project References, TypeScript will expect to verify that the outputs of referenced projects are up-to-date with respect to their inputs. (This is true even without using the --build option). When using a non-sandboxed spawn strategy, tsc can read the sources from other ts_project rules in your project, and will expect that the tsconfig.json file for those references will indicate where the outputs were written. However the outDir is determined by this Bazel rule so it cannot be known from reading the tsconfig.json file. This problem is manifested as a TypeScript diagnostic like error TS6305: Output file '/path/to/execroot/a.d.ts' has not been built from source file '/path/to/execroot/a.ts'. As a workaround, you can give the Windows "fastbuild" output directory as the outDir in your tsconfig file. On other platforms, the value isn't read so it does no harm. See as an example. We hope this will be fixed in a future release of TypeScript; follow

  3. When TypeScript encounters an import statement, it adds the source file resolved by that reference to the program. However you may have included that source file in a different project, so this causes the problem mentioned above where a source file is in multiple programs. (Note, if you use Project References this is not the case, TS will know the referenced file is part of the other program.) This will result in duplicate emit for the same file, which produces an error since the files written to the output tree are read-only. Workarounds include using using Project References, or simply grouping the whole compilation into one program (if this doesn't exceed your time budget).


A name for the target.

We recommend you use the basename (no .json extension) of the tsconfig file that should be compiled.


Label of the tsconfig.json file to use for the compilation

To support "chaining" of more than one extended config, this label could be a target that provdes TsConfigInfo such as ts_config.

By default, we assume the tsconfig file is named by adding .json to the name attribute.

EXPERIMENTAL: generated tsconfig

Instead of a label, you can pass a dictionary of tsconfig keys.

In this case, a tsconfig.json file will be generated for this compilation, in the following way:

  • all top-level keys will be copied by converting the dict to json. So tsconfig = {"compilerOptions": {"declaration": True}} will result in a generated tsconfig.json with {"compilerOptions": {"declaration": true}}
  • each file in srcs will be converted to a relative path in the files section.
  • the extends attribute will be converted to a relative path

Note that you can mix and match attributes and compilerOptions properties, so these are equivalent:

    tsconfig = {
        "compilerOptions": {
            "declaration": True,


    declaration = True,


List of labels of TypeScript source files to be provided to the compiler.

If absent, defaults to **/*.ts[x] (all TypeScript files in the package).


List of strings of additional command-line arguments to pass to tsc.


List of labels of other rules that produce TypeScript typings (.d.ts files)


Label of the tsconfig file referenced in the extends section of tsconfig

To support "chaining" of more than one extended config, this label could be a target that provdes TsConfigInfo such as ts_config.

DEPRECATED, to be removed in 3.0: For backwards compatibility, this accepts a list of Labels of the "chained" tsconfig files. You should instead use a single Label of a ts_config target. Follow this deprecation:


boolean; Specifies whether TypeScript will read .js and .jsx files. When used with declaration, TypeScript will generate .d.ts files from .js files.


if the declaration bit is set in the tsconfig. Instructs Bazel to expect a .d.ts output for each .ts source.


if the sourceMap bit is set in the tsconfig. Instructs Bazel to expect a output for each .ts source.


if the declarationMap bit is set in the tsconfig. Instructs Bazel to expect a output for each .ts source.


if the composite bit is set in the tsconfig. Instructs Bazel to expect a .tsbuildinfo output and a .d.ts output for each .ts source.


if the incremental bit is set in the tsconfig. Instructs Bazel to expect a .tsbuildinfo output.


if the emitDeclarationOnly bit is set in the tsconfig. Instructs Bazel not to expect .js or outputs for .ts sources.


the user-specified value of tsBuildInfoFile from the tsconfig. Helps Bazel to predict the path where the .tsbuildinfo output is written.


Label of the TypeScript compiler binary to run.

For example, tsc = "@my_deps//typescript/bin:tsc" Or you can pass a custom compiler binary instead.


Label of the TypeScript compiler binary to run when running in worker mode.

For example, tsc = "@my_deps//node_modules/typescript/bin/tsc" Or you can pass a custom compiler binary instead.


Label of the package containing all data deps of worker_tsc_bin.

For example, tsc = "@my_deps//typescript"


boolean; whether to check that the tsconfig settings match the attributes.


Experimental! Use only with caution.

Allows you to enable the Bazel Persistent Workers strategy for this project. See

This requires that the tsc binary support a --watch option.

NOTE: this does not work on Windows yet. We will silently fallback to non-worker mode on Windows regardless of the value of this attribute. Follow for progress on this feature.


a string specifying a subdirectory under the bazel-out folder where generated declaration outputs are written. Equivalent to the TypeScript --declarationDir option. By default declarations are written to the out_dir.


a string specifying a subdirectory under the bazel-out folder where outputs are written. Equivalent to the TypeScript --outDir option. Note that Bazel always requires outputs be written under a subdirectory matching the input package, so if your rule appears in path/to/my/package/BUILD.bazel and out_dir = "foo" then the .js files will appear in bazel-out/[arch]/bin/path/to/my/package/foo/*.js. By default the out_dir is '.', meaning the packages folder in bazel-out.


a string specifying a subdirectory under the input package which should be consider the root directory of all the input files. Equivalent to the TypeScript --rootDir option. By default it is '.', meaning the source directory where the BUILD file lives.

Link the workspace root to the bin_dir to support absolute requires like 'my_wksp/path/to/file'. If source files need to be required then they can be copied to the bin_dir with copy_to_bin.


passed through to underlying rule, allows eg. visibility, tags