angular-cn/public/docs/ts/latest/quickstart.jade

block includes
  include _util-fns
  - var _Install = 'Install'
  - var _prereq = 'Node.js'
  - var _angular_browser_uri = '@angular/platform-browser-dynamic'
  - var _angular_core_uri = '@angular/core'
  - var _appDir = 'app'
  - var _indexHtmlDir = 'project root'

:marked
  Our QuickStart goal is to build and run a super-simple
  Angular 2 application in #{_Lang}, and
  establish a development environment for the remaining documentation samples
  that also can be the foundation for real world applications.

.callout.is-helpful
  header Don't want #{_Lang}?
  p.
    Although we're getting started in #{_Lang}, you can also write Angular 2 apps
    in #{_docsFor == 'ts' ? 'Dart' : 'TypeScript'} and JavaScript.
    Just select either of those languages from the combo-box in the banner.

h1 Try it!
p
  | Try the #[+liveExampleLink2('live example', 'quickstart')] which loads the sample app
  +ifDocsFor('ts')
    |  in #[a(href="http://plnkr.co/" title="Plunker" target="_blank") plunker]
  |  and displays the simple message:

figure.image-display
  img(src='/resources/images/devguide/quickstart/my-first-app.png' alt="Output of QuickStart app")

h1 Build this app!
:marked
  - [Prerequisite](#prereq): Install #{_prereq}
  - [Step 1](#create-and-configure): Create the app’s project folder and
    define package dependencies and special project setup
  - [Step 2](#root-component): Create the app’s Angular root component
  - [Step 3](#main): Add `main.#{_docsFor}`, identifying the root component to Angular
  - [Step 4](#index): Add `index.html`, the web page that hosts the application
  - [Step 5](#build-and-run): Build and run the app
  - [Make some changes to the app](#make-some-changes)
  - [Wrap up](#wrap-up)

.l-main-section
h2#prereq Prerequisite: #{_prereq}

block setup-tooling
  :marked
    Install **[Node.js® and npm](https://nodejs.org/en/download/)**
    if they are not already on your machine.

block download-source
  .l-main-section
  .callout.is-helpful
    header Download the source
    :marked
      Instead of following each step of these instructions, we can
      [download the QuickStart source](https://github.com/angular/quickstart/blob/master/README.md)
      from github and follow its brief instructions.

.l-main-section
button(class="verbose off md-primary md-button md-ink-ripple", type="button", onclick="verbose(false)").
  Hide explanations
button(class="verbose on md-primary md-button md-ink-ripple", type="button", onclick="verbose(true)").
  View explanations
.l-verbose-section
  :marked
    *Explanations* describe the concepts and reasons behind the instructions.
    Explanations have a thin border on the left like *this* block of text.

    Click *Hide Explanations* to show only the instructions.
    Click *View Explanations* to see everything again.

.l-sub-section
  :marked
    We'll see many code blocks as we build the QuickStart app. They're all easy to copy and paste:
  code-example(format="nocode").
    Click the glyph on the right to copy code snippets to the clipboard  ==>

.l-main-section
h2#create-and-configure Step 1: Create and configure the project

- var _package_and_config_files = _docsFor == 'dart' ? 'pubspec.yaml' : 'package definition and configuration files'

:marked
  In this step we:
  * [(a) Create the project folder](#create-the-project-folder)
  * [(b) Add #{_package_and_config_files}](#add-config-files)
  * [(c) #{_Install} packages](#install-packages)

h3 (a) Create the project folder

code-example(language="sh").
  mkdir angular2-quickstart
  cd    angular2-quickstart

h3#add-config-files (b) Add #{_package_and_config_files}
block package-and-config-files
  - var _tsconfigUri = 'guide/typescript-configuration.html#tsconfig'
  - var _typingsUri = 'guide/typescript-configuration.html#!#typings'

  p Add the following package definition and configuration files to the project folder:
  ul
    li.
      #[b package.json] lists packages the QuickStart app depends on and
      defines some useful scripts.
      See #[a(href="guide/npm-packages.html") Npm Package Configuration] for details.
    li.
      #[b tsconfig.json] is the TypeScript compiler configuration file.
      See #[a(href="#{_tsconfigUri}") TypeScript Configuration] for details.
    li.
      #[b typings.json] identifies TypeScript definition files.
      See #[a(href="#{_typingsUri}") TypeScript Configuration] for details.
    li.
      #[b systemjs.config.js], the SystemJS configuration file.
      See discussion #[a(href="#systemjs") below].

  a#config-files
  +makeTabs(`
      quickstart/ts/package.1.json,
      quickstart/ts/tsconfig.1.json,
      quickstart/ts/typings.1.json,
      quickstart/ts/systemjs.config.1.js
    `, '', `
      package.json,
      tsconfig.json,
      typings.json,
      systemjs.config.js
    `)

h3#install-packages (c) #{_Install} packages
block install-packages
  :marked
    We install the packages listed in `package.json` using `npm`. Enter the
    following command in a terminal window (command window in Windows):

  code-example(language="sh").
    npm install

  .alert.is-important
    :marked
      Scary <span style="color:red; font-weight: bold">error messages in red</span> may appear **during** install.
      The install typically recovers from these errors and finishes successfully.
    .l-verbose-section(class="l-verbose-inherit")
      :marked
        #### npm errors and warnings

        All is well if there are no console messages starting with `npm ERR!` *at the end* of **npm install**.
        There might be a few `npm WARN` messages along the way &mdash; and that is perfectly fine.

        We often see an `npm WARN` message after a series of `gyp ERR!` messages.
        Ignore them. A package may try to recompile itself using `node-gyp`.
        If the recompile fails, the package recovers (typically with a pre-built version)
        and everything works.

        Just make sure there are no `npm ERR!` messages at the end of `npm install`.

  .l-verbose-section
    :marked
      #### Adding the libraries and packages we need with *npm*
      Angular application developers rely on the _[npm](https://docs.npmjs.com)_
      package manager to install the libraries and packages their apps require.
      The Angular team recommends the starter-set of packages specified in the
      `dependencies` and `devDependencies` sections.
      See the [npm packages](guide/npm-packages.html) chapter for details.

      #### Helpful scripts
      We've included a number of npm scripts in our suggested `package.json` to handle common development tasks:
    +makeJson('quickstart/ts/package.1.json',{ paths: 'scripts'}, 'package.json (scripts)')(format=".")

    :marked
      We execute most npm scripts in the following way: `npm run` followed by a *script-name*.
      Some commands (such as `start`) don't require the `run` keyword.

      Here's what these scripts do:

      * `npm start` - runs the compiler and a server  at the same time, both in "watch mode"

      * `npm run tsc` - runs the TypeScript compiler once

      * `npm run tsc:w` - runs the TypeScript compiler in watch mode;
      the process keeps running, awaiting changes to TypeScript files and recompiling when it sees them

      * `npm run lite` - runs the <a href="https://www.npmjs.com/package/lite-server" target="_blank">lite-server</a>,
      a light-weight, static file server with excellent support for Angular apps that use routing

      * `npm run typings` - runs the [*typings* tool](#{_typingsUri}) separately

      * `npm run postinstall` - called by *npm* automatically *after* it successfully completes package installation.
      This script installs the [TypeScript definition files](#{_typingsUri}) defined in `typings.json`

:marked
  **We're all set.** Let's write some code.

.l-main-section
h2#root-component Step 2: Our first Angular component
:marked
  Let's create a folder to hold our application and add a super-simple Angular component.

  **Create #{_an} #{_appDir} subfolder** off the project root directory:

code-example.
  mkdir #{_appDir}

a#app-component
p.
  #[b Create the component file]
  #[code #[+adjExPath('app/app.component.ts')]] (in this newly created directory) with the following content:

+makeProjExample('app/app.component.ts')

.l-verbose-section
  :marked
    ### AppComponent is the root of the application

    Every Angular app has at least one **root component**, conventionally named `AppComponent`,
    that hosts the client user experience.
    Components are the basic building blocks of Angular applications.
    A component controls a portion of the screen &mdash; a *view* &mdash; through its associated template.

    This QuickStart has only one, extremely simple component.
    But it has the essential structure of every component we'll ever write:

    * One or more [import](#component-import)
    statements to reference the things we need.
    * A [@Component #{_decorator}](#component-decorator)
    that tells Angular what template to use and how to create the component.
    * A [component class](#component-class)
    that controls the appearance and behavior of a view through its template.

  a#component-import
  :marked
    ### Import

    Angular apps are modular. They consist of many files each dedicated to a purpose.
    Angular itself is modular. It is a collection of library modules
    each made up of several, related features that we'll use to build our application.

    When we need something from a module or library, we import it.
    Here we import the Angular 2 core so that our component code can have access to
    the `@Component` #{_decorator}.

  +makeExcerpt('app/app.component.ts', 'import')

  h3#component-decorator @Component #{_decorator}
  +ifDocsFor('ts')
    :marked
      `Component` is a *decorator function* that takes a *metadata object* as argument.
      We apply this function to the component class by prefixing the function with the
      **@** symbol and invoking it with a metadata object, just above the class.
  :marked
    `@Component` is #{_a} *#{_decorator}* that allows us to associate *metadata* with the
    component class.
    The metadata tells Angular how to create and use this component.

  +makeExcerpt('app/app.component.ts', 'metadata')

  block annotation-fields
    :marked
      This particular metadata object has two fields, a `selector` and a `template`.
  :marked
    The **selector** specifies a simple CSS selector for an HTML element that represents the component.

    >The element for this component is named `my-app`.
    Angular creates and displays an instance of our `AppComponent`
    wherever it encounters a `my-app` element in the host HTML.

    The **template** specifies the component's companion template,
    written in an enhanced form of HTML that tells Angular how to render this component's view.

    >Our template is a single line of HTML announcing "*My First Angular 2 App*".

    >A more advanced template could contain data bindings to component properties
    and might identify other application components which have their own templates.
    These templates might identify yet other components.
    In this way an Angular application becomes a tree of components.

  :marked
    ### Component class
    At the bottom of the file is an empty, do-nothing class named `AppComponent`.
  +makeExcerpt('app/app.component.ts', 'class')
  :marked
    When we're ready to build a substantive application,
    we can expand this class with properties and application logic.
    Our `AppComponent` class is empty because we don't need it to do anything in this QuickStart.
  +ifDocsFor('ts')
    :marked
      We **export** `AppComponent` so that we can **import** it elsewhere in our application,
      as we'll see when we create `main.ts`.

.l-main-section
h2#main Step 3: Add #[code #[+adjExPath('main.ts')]]

block create-main
  p.
    Now we need something to tell Angular to load the root component.
    Create the file #[code #[+adjExPath('app/main.ts')]] with the following content:

+makeProjExample('app/main.ts')

.l-verbose-section
  :marked
    We import the two things we need to launch the application:

    1. Angular's browser `bootstrap` function
    1. The application root component, `AppComponent`.

    Then we call `bootstrap` with `AppComponent`.

    ### Bootstrapping is platform-specific
    Notice that we import the `bootstrap` function from `#{_angular_browser_uri}`,
    not `#{_angular_core_uri}`.
    Bootstrapping isn't core because there isn't a single way to bootstrap the app.
    True, most applications that run in a browser call the bootstrap function from
    this library.

    But it is possible to load a component in a different environment.
    We might load it on a mobile device with [Apache Cordova](https://cordova.apache.org/) or [NativeScript](https://www.nativescript.org/).
    We might wish to render the first page of our application on the server
    to improve launch performance or facilitate
    [SEO](http://www.google.com/webmasters/docs/search-engine-optimization-starter-guide.pdf).
    These targets require a different kind of bootstrap function that we'd import from a different library.

    ### Why create separate *main.#{_docsFor}* and app component files?

    Both `main.#{_docsFor}` and the app component files are tiny.
    This is just a QuickStart.
    We could have merged these two files into one
    and spared ourselves some complexity.

    We'd rather demonstrate the proper way to structure an Angular application.
    App bootstrapping is a separate concern from presenting a view.
    Mixing concerns creates difficulties down the road.
    We might launch the `AppComponent` in multiple environments with different bootstrappers.
    Testing the component is much easier if it doesn't also try to run the entire application.
    Let's make the small extra effort to do it *the right way*.

.l-main-section
h2#index Step 4: Add #[code index.html]
:marked
  In the *#{_indexHtmlDir}* folder
  create an `index.html` file and paste the following lines into it:

+makeProjExample('index.html')

.l-verbose-section
  :marked
    The `index.html` file defines the web page that hosts the application.

  block index-html-commentary-for-ts
    :marked
      The noteworthy sections of HTML are:

      1. The JavaScript [libraries](#libraries)
      2. Configuration file for [SystemJS](#systemjs), and a script
         where we import and run the `app` module which refers to the `main` file that we just wrote.
      3. The [`<my-app>`](#my-app) tag in the `<body>` which is *where our app lives!*

    :marked
      ### Libraries
      We loaded the following scripts
    +makeExcerpt('index.html', 'libraries')
    :marked
      We begin with `core-js`'s ES2015/ES6 shim which monkey patches the global context (window) with essential features of ES2015 (ES6).
      Next are the polyfills for Angular2, `zone.js` and `reflect-metadata`.
      Then the [SystemJS](#systemjs) library for module loading.

      We'll make different choices as we gain experience and
      become more concerned about production qualities such as
      load times and memory footprint.

    h3#systemjs SystemJS
    :marked
      QuickStart uses <a href="https://github.com/systemjs/systemjs" target="_blank">SystemJS</a>
      to load application and library modules. [Earlier](#add-config-files) we
      added the `systemjs.config.js` file to the project root.
      There are alternatives that work just fine including the well-regarded
      [webpack](guide/webpack.html).
      SystemJS happens to be a good choice.
      But we want to be clear that it was a *choice* and not a *preference*.

      All module loaders require configuration and all loader configuration
      becomes complicated rather quickly as soon as the file structure diversifies and
      we start thinking about building for production and performance.

      We suggest becoming well-versed in the loader of your choice.
      Learn more about SystemJS configuration
      <a href="https://github.com/systemjs/systemjs/blob/master/docs/config-api.md" target="_blank">here</a>.

      With those cautions in mind, what are we doing in the
      QuickStart [`systemjs.config.js` configuration file we added earlier](#config-files)?
      First, we create a map to tell SystemJS where to look when we import some module.
      Then, we register all our packages to SystemJS:
      all the project dependencies and our application package, `app`.

    .l-sub-section
      :marked
        Our QuickStart doesn't use all of the listed packages
        but any substantial application will want many of them
        and all of the listed packages are required by at least one of the documentation samples.

        There is no runtime harm in listing packages that we don't need as they will only be loaded when requested.
    :marked
      The `app` package tells SystemJS what to do when it sees a request for a
      module from the `app/` folder.

      Our QuickStart makes such requests when one of its
      application TypeScript files has an import statement like this:
    +makeExcerpt('app/main.ts', 'import')
    :marked
      Notice that the module name (after `from`) does not mention a filename extension.
      In the configuration we tell SystemJS to default the extension to `js`, a JavaScript file.

      That makes sense because we transpile TypeScript to JavaScript
      *before* running the application.

    .l-sub-section
      :marked
        #### Transpiling in the browser
        In the live example on plunker we transpile (AKA compile) to JavaScript in the browser
        on the fly. _That's fine for a demo_.

        **Do not transpile in the browser during development or for production**.

        We strongly recommend transpiling (AKA compiling) to JavaScript during a build phase
        before running the application for several reasons including:

        * We see compiler warnings and errors that are hidden from us in the browser.

        * Precompilation simpifies the module loading process and
        it's much easier to diagnose problems when this is a separate, external step.

        * Precompilation means a faster user experience because the browser doesn't waste time compiling.

        * We iterate development faster because we only recompile changed files.
        We notice the difference as soon as the app grows beyond a handful of files.

        * Precompilation fits into a continuous integration process of build, test, deploy.

    :marked
      The `System.import` call tells SystemJS to import the `main` file
      (`main.js` ... after transpiling `main.ts`, remember?);
      `main` is where we tell Angular to launch the application.
      We also catch and log launch errors to the console.

      All other modules are loaded upon request
      either by an import statement or by Angular itself.

      ### *&lt;my-app&gt;*

  a(id="my-app")
  :marked
    When Angular calls the `bootstrap` function in `main.#{_docsFor}`, it reads the `AppComponent`
    metadata, finds the `my-app` selector, locates an element tag named `my-app`,
    and renders our application's view between those tags.

:marked
  ### Add some style
  Styles aren't essential but they're nice, and `index.html` assumes we have
  a stylesheet called `styles.css`.

  Create a `styles.css` file in the *#{_indexHtmlDir}* folder and start styling, perhaps with the minimal
  styles shown below. For the full set of master styles used by the documentation samples,
  see [styles.css](https://github.com/angular/angular.io/blob/master/public/docs/_examples/styles.css).
+makeExcerpt('styles.1.css')

.l-main-section
h2#build-and-run Step 5: Build and run the app!
block run-app
  :marked
    Open a terminal window and enter this command:
  code-example.
    npm start
  :marked
    That command runs two parallel node processes
    1. The TypeScript compiler in watch mode
    1. A static server called **lite-server** that loads `index.html` in a browser
    and refreshes the browser when application files change

    In a few moments, a browser tab should open and display

figure.image-display
  img(src='/resources/images/devguide/quickstart/my-first-app.png' alt="Output of QuickStart app")

:marked
  **Great job!**

block build-app
  //- Nothing for ts.

:marked
  ## Make some changes

  Try changing the message to "My SECOND Angular 2 app".
block server-watching
  :marked
    The TypeScript compiler and `lite-server` are watching.
    They should detect the change, recompile the TypeScript into JavaScript,
    refresh the browser, and display the revised message.
    It's a nifty way to develop an application!

    We close the terminal window when we're done to terminate both the compiler and the server.

.l-main-section
:marked
  # Wrap up

  Our final project folder structure looks like this:
block project-file-structure
  .filetree
    .file angular2-quickstart
    .children
      .file app
      .children
        .file app.component.ts
        .file main.ts
      .file node_modules ...
      .file typings ...
      .file index.html
      .file package.json
      .file styles.css
      .file systemjs.config.js
      .file tsconfig.json
      .file typings.json
:marked
  Here are the file contents:

block project-files
  +makeTabs(`
      quickstart/ts/app/app.component.ts,
      quickstart/ts/app/main.ts,
      quickstart/ts/index.html,
      quickstart/ts/package.1.json,
      quickstart/ts/tsconfig.1.json,
      quickstart/ts/typings.1.json,
      quickstart/ts/styles.1.css,
      quickstart/ts/systemjs.config.1.js`
    ,null,
    `app/app.component.ts,
    app/main.ts,
    index.html,
    package.json,
    tsconfig.json,
    typings.json,
    styles.css,
    systemjs.config.js`)

.l-main-section
:marked
  ## What next?
  Our first application doesn't do much. It's basically "Hello, World" for Angular 2.

  We kept it simple in our first pass: we wrote a little Angular component,
  created a simple `index.html`, and launched with a
  static file server. That's about all we'd expect to do for a "Hello, World" app.

  **We have greater ambitions!**
block what-next-ts-overhead
  :marked
    The good news is that the overhead of setup is (mostly) behind us.
    We'll probably only touch the `package.json` to update libraries.
    We'll likely open `index.html` only if we need to add a library or some css stylesheets.
:marked
  We're about to take the next step and build a small application that
  demonstrates the great things we can build with Angular 2.

  Join us on the [Tour of Heroes Tutorial](./tutorial)!