diff --git a/aio/content/guide/language-service.md b/aio/content/guide/language-service.md index 80c6b12b40..498e0a88aa 100644 --- a/aio/content/guide/language-service.md +++ b/aio/content/guide/language-service.md @@ -1,43 +1,50 @@ # Angular Language Service -The Angular Language Service is a way to get completions, errors, -hints, and navigation inside your Angular templates whether they -are external in an HTML file or embedded in annotations/decorators -in a string. The Angular Language Service autodetects that you are -opening an Angular file, reads your `tsconfig.json` file, finds all the -templates you have in your application, and then provides language -services for any templates that you open. +The Angular Language Service provides code editors with a way to get completions, errors, +hints, and navigation inside Angular templates. +It works with external templates in separate HTML files, and also with in-line templates. + +## Features + +Your editor autodetects that you are opening an Angular file. +It then uses the Angular Language Service to read your `tsconfig.json` file, find all the +templates you have in your application, and then provide language services for any templates that you open. + +Language services include: + +* Completions lists +* AOT Diagnostic messages +* Quick info +* Go to definition -## Autocompletion +### Autocompletion Autocompletion can speed up your development time by providing you with -contextual possibilities and hints as you type. This example shows -autocomplete in an interpolation. As you type it out, +contextual possibilities and hints as you type. +This example shows autocomplete in an interpolation. As you type it out, you can hit tab to complete.
autocompletion
-There are also completions within -elements. Any elements you have as a component selector will +There are also completions within elements. Any elements you have as a component selector will show up in the completion list. -## Error checking +### Error checking -The Angular Language Service can also forewarn you of mistakes in your code. +The Angular Language Service can forewarn you of mistakes in your code. In this example, Angular doesn't know what `orders` is or where it comes from.
error checking
-## Navigation +### Quick info and navigation -Navigation allows you to hover to -see where a component, directive, module, etc. is from and then -click and press F12 to go directly to its definition. +The quick-info feature allows you to hover to see where components, directives, modules, and so on come from. +You can then click "Go to definition" or press F12 to go directly to the definition.
navigation @@ -46,41 +53,28 @@ click and press F12 to go directly to its definition. ## Angular Language Service in your editor -Angular Language Service is currently available for [Visual Studio Code](https://code.visualstudio.com/) and -[WebStorm](https://www.jetbrains.com/webstorm). +Angular Language Service is currently available as an extension for [Visual Studio Code](https://code.visualstudio.com/), +[WebStorm](https://www.jetbrains.com/webstorm), and [Sublime Text](https://www.sublimetext.com/). ### Visual Studio Code -In Visual Studio Code, install Angular Language Service from the store, -which is accessible from the bottom icon on the left menu pane. -You can also use the VS Quick Open (⌘+P on Mac, CTRL+P on Windows) to search for the extension. When you've opened it, -enter the following command: - -```sh -ext install Angular.ng-template -``` - -Then click the install button to install the Angular Language Service. +In [Visual Studio Code](https://code.visualstudio.com/), install the extension from the [Extensions: Marketplace](https://marketplace.visualstudio.com/items?itemName=Angular.ng-template). You can open the marketplace from the editor using the Extensions icon on the left menu pane, or use VS Quick Open (⌘+P on Mac, CTRL+P on Windows) and type "? ext". +In the marketplace, search for Angular Language Service extension, and click the **Install** button. ### WebStorm -In webstorm, you have to install the language service as a dev dependency. -When Angular sees this dev dependency, it provides the -language service inside of WebStorm. Webstorm then gives you -colorization inside the template and autocomplete in addition to the Angular Language Service. +In [WebStorm](https://www.jetbrains.com/webstorm/), you must install the language service package as a project dependency. -Here's the dev dependency -you need to have in `package.json`: +1. Add the following to your `devDependencies` in your project's `package.json` -```json + devDependencies { "@angular/language-service": "^6.0.0" } -``` + -Then in the terminal window at the root of your project, -install the `devDependencies` with `npm` or `yarn`: +2. In the terminal window at the root of your project, install the `devDependencies` with `npm` or `yarn`: ```sh npm install @@ -97,79 +91,72 @@ yarn yarn install ``` +When Angular sees this dev dependency, it provides the language service in the WebStorm environment. +WebStorm then gives you colorization inside the template and autocomplete in addition to the Angular Language Service. + ### Sublime Text -In [Sublime Text](https://www.sublimetext.com/), you first need an extension to allow Typescript. -Install the latest version of typescript in a local `node_modules` directory: +In [Sublime Text](https://www.sublimetext.com/), the Language Service supports only in-line templates when installed as a plug-in. +You need a custom Sublime plug-in (or modifications to the current plug-in) for completions in HTML files. + +To use the Language Service for in-line templates, you must first add an extension to allow TypeScript, then install the Angular Language Service plug-in. Starting with TypeScript 2.3, TypeScript has a plug-in model that the language service can use. + +1. Install the latest version of TypeScript in a local `node_modules` directory: ```sh npm install --save-dev typescript ``` -Then install the Angular Language Service in the same location: -```sh -npm install --save-dev @angular/language-service -``` - -Starting with TypeScript 2.3, TypeScript has a language service plugin model that the language service can use. - -Next, in your user preferences (`Cmd+,` or `Ctrl+,`), add: - -```json -"typescript-tsdk": "/node_modules/typescript/lib" -``` - - -## Installing in your project - -You can also install Angular Language Service in your project with the -following `npm` command: +2. Install the Angular Language Service package in the same location: ```sh npm install --save-dev @angular/language-service ``` -Additionally, add the following to the `"compilerOptions"` section of -your project's `tsconfig.json`. -```json +3. Once the package is installed, add the following to the `"compilerOptions"` section of your project's `tsconfig.json`. + + "plugins": [ {"name": "@angular/language-service"} ] -``` -Note that this only provides diagnostics and completions in `.ts` -files. You need a custom sublime plugin (or modifications to the current plugin) -for completions in HTML files. + + +4. In your editor's user preferences (`Cmd+,` or `Ctrl+,`), add the following: + + +"typescript-tsdk": "/node_modules/typescript/lib" + + +This allows the Angular Language Service to provide diagnostics and completions in `.ts` files. + + ## How the Language Service works -When you use an editor with a language service, there's an -editor process which starts a separate language process/service -to which it speaks through an [RPC](https://en.wikipedia.org/wiki/Remote_procedure_call). -Any time you type inside of the editor, it sends information to the other process to -track the state of your project. When you trigger a completion list within a template, the editor process first parses the template into an HTML AST, or [abstract syntax tree](https://en.wikipedia.org/wiki/Abstract_syntax_tree). Then the Angular compiler interprets -what module the template is part of, the scope you're in, and the component selector. Then it figures out where in the template AST your cursor is. When it determines the -context, it can then determine what the children can be. - -It's a little more involved if you are in an interpolation. If you have an interpolation of `{{data.---}}` inside a `div` and need the completion list after `data.---`, the compiler can't use the HTML AST to find the answer. The HTML AST can only tell the compiler that there is some text with the characters "`{{data.---}}`". That's when the template parser produces an expression AST, which resides within the template AST. The Angular Language Services then looks at `data.---` within its context and asks the TypeScript Language Service what the members of data are. TypeScript then returns the list of possibilities. - - -For more in-depth information, see the -[Angular Language Service API](https://github.com/angular/angular/blob/master/packages/language-service/src/types.ts) - - - - - +When you use an editor with a language service, the editor starts a separate language-service process +and communicates with it through an [RPC](https://en.wikipedia.org/wiki/Remote_procedure_call), using the [Language Server Protocol](https://microsoft.github.io/language-server-protocol/). +When you type into the editor, the editor sends information to the language-service process to +track the state of your project. +When you trigger a completion list within a template, the editor first parses the template into an +HTML [abstract syntax tree (AST)](https://en.wikipedia.org/wiki/Abstract_syntax_tree). +The Angular compiler interprets that tree to determine the context: which module the template is part of, the current scope, the component selector, and where your cursor is in the template AST. It can then determine the symbols that could potentially be at that position.. +It's a little more involved if you are in an interpolation. +If you have an interpolation of `{{data.---}}` inside a `div` and need the completion list after `data.---`, the compiler can't use the HTML AST to find the answer. +The HTML AST can only tell the compiler that there is some text with the characters "`{{data.---}}`". +That's when the template parser produces an expression AST, which resides within the template AST. +The Angular Language Services then looks at `data.---` within its context, asks the TypeScript Language Service what the members of `data` are, and returns the list of possibilities.
-## More on Information +## More information -For more information, see [Chuck Jazdzewski's presentation](https://www.youtube.com/watch?v=ez3R0Gi4z5A&t=368s) on the Angular Language -Service from [ng-conf](https://www.ng-conf.org/) 2017. +* For more in-depth information on the implementation, see the +[Angular Language Service API](https://github.com/angular/angular/blob/master/packages/language-service/src/types.ts). +* For more on the design considerations and intentions, see [design documentation here](https://github.com/angular/vscode-ng-language-service/wiki/Design). +* See also [Chuck Jazdzewski's presentation](https://www.youtube.com/watch?v=ez3R0Gi4z5A&t=368s) on the Angular Language Service from [ng-conf](https://www.ng-conf.org/) 2017.