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angular2-template-compiler

Angular Template Compiler

Angular applications are built with templates, which may be .html or .css files, or may be inline template attributes on Decorators like @Component.

These templates are compiled into executable JS at application runtime (except in interpretation mode). This compilation can occur on the client, but it results in slower bootstrap time, and also requires that the compiler be included in the code downloaded to the client.

You can produce smaller, faster applications by running Angular's compiler as a build step, and then downloading only the executable JS to the client.

Install and use

$ npm install angular2-template-compiler typescript@next rxjs @angular/compiler
# Optional sanity check, make sure TypeScript can compile
$ ./node_modules/.bin/tsc -p path/to/project
$ ./node_modules/.bin/ng2tc -p path/to/project

In order to write a bootstrap that imports the generated code, you should first write your top-level component, and run ng2tc once to produce a generated .ngfactory.ts file. Then you can add an import statement in the bootstrap allowing you to bootstrap off the generated code.

Configuration

The tsconfig.json file may contain an additional configuration block:

 "angularCompilerOptions": {
   "genDir": "."
 }

the genDir option controls the path (relative to tsconfig.json) where the generated file tree will be written. If genDir is not set, then the code will be generated in the source tree, next to your original sources. More options may be added as we implement more features.

We recommend you avoid checking generated files into version control. This permits a state where the generated files in the repository were created from sources that were never checked in, making it impossible to reproduce the current state. Also, your changes will effectively appear twice in code reviews, with the generated version inscrutible by the reviewer.

In TypeScript 1.8, the generated sources will have to be written alongside your originals, so set genDir to the same location as your files (typicially the same as rootDir). Add **/*.ngfactory.ts to your .gitignore or other mechanism for your version control system.

In TypeScript 1.9 and above, you can add a generated folder into your application, such as codegen. Using the rootDirs option, you can allow relative imports like import {} from './foo.ngfactory' even though the src and codegen trees are distinct. Add **/codegen to your .gitignore or similar.

Note that in the second option, TypeScript will emit the code into two parallel directories as well. This is by design, see https://github.com/Microsoft/TypeScript/issues/8245. This makes the configuration of your runtime module loader more complex, so we don't recommend this option yet.

See the example in the test/ directory for a working example.

Compiler CLI

This program mimics the TypeScript tsc command line. It accepts a -p flag which points to a tsconfig.json file, or a directory containing one.

This CLI is intended for demos, prototyping, or for users with simple build systems that run bare tsc.

Users with a build system should expect an Angular 2 template plugin. Such a plugin would be based on the index.ts in this directory, but should share the TypeScript compiler instance with the one already used in the plugin for TypeScript typechecking and emit.

Design

At a high level, this program

  • collects static metadata about the sources using the ts-metadata-collector package in angular2
  • uses the OfflineCompiler from angular2/src/compiler/compiler to codegen additional .ts files
  • these .ts files are written to the genDir path, then compiled together with the application.

For developers

Run the compiler from source:

# Build angular2
gulp build.js.cjs
# Build the compiler
./node_modules/.bin/tsc -p tools/compiler_cli/src
# Run it on the test project
node ./dist/js/cjs/compiler_cli -p tools/compiler_cli/test

Release:

$ gulp test.compiler_cli
$ cp tools/compiler_cli/README.md tools/compiler_cli/package.json dist/tools/compiler_cli
# npm login as angularcore
$ npm publish dist/tools/compiler_cli