angular-cn/public/docs/dart/latest/guide/user-input.jade

.l-main-section
  p.
    Use the event syntax <strong>(<em>eventName</em>)</strong> to
    make your application respond to user input.
  p.
    You can specify the event handler—a method in the component controller—like this:

  code-example(language="html").
    &lt;input (keyup)="myControllerMethod()"&gt;
  p.
    As in previous examples, you can make element references available to
    other parts of the template as a local
    variable using the <b>#</b> syntax.
    Using <code>#</code> and events,
    you can write the old "update text as you type" example:
    <!-- PENDING: make sure we use recommended word separation scheme.
    my-name doesn't work, but my_name does. Would myName work? -->

  code-example(language="html").
    &lt;input #myname (keyup)&gt;
    &lt;p&gt;{{myname.value}}&lt;/p&gt;

  p.text-body(ng-non-bindable).
    In that example, <code>#myname</code> creates a local variable in the template that
    the <code>&lt;p&gt;</code> element can refer to.
    The <code>(keyup)</code> tells Angular to trigger updates when it gets a keyup
    event.  And <code>{{myname.value}}</code> binds the text node of the
    <code>&lt;p&gt;</code> element to the
    input's value property.

  p.
    Let's do something a little more complex, where the user enters items
    that the app adds to a list:
  figure.image-display
    img(src='/resources/images/examples/user-input-example1.png' alt="Example of Todo App")


.l-main-section
  h2#section-create-an-array-property Create a list property
  p.
    With the default files in place,
    create a TodoController class to manage interactions with the
    list. Inside TodoController, add a list with some initial items.
    Then add a method that adds new items
    to the list.

  code-example(language="dart").
    class TodoList {
      List&lt;String&gt; todos =[
        'Eat breakfast',
        'Walk dog',
        'Breathe',
        'Learn Angular'
      ];

      addTodo(String todo) {
        todos.add(todo);
      }
    }

.callout.is-helpful
  header Production Best Practice
  p.
      As shown in the previous example, a production application you would
      separate the model out into another class
      and inject it into <code>TodoController</code>.
      We've omitted that here for brevity.

<br><br><!-- PENDING: fix formatting of main sections after callouts -->

.l-main-section
  h2#section-display-the-list-of-todos Display the list of todos
  p.
    Using the <code>*ng-for</code> iterator, create an <code>&lt;li&gt;</code> for each item in the todos list and set
    its text to the value.

  code-example(language="html").
    &lt;ul&gt;
       &lt;li *ng-for=&quot;#todo of todos&quot;&gt;
         {{ todo }}
       &lt;/li&gt;
    &lt;/ul&gt;

.l-main-section
  h2#section-add-todos-to-the-list Add todos to the list via button click
  p.
    Now, add a text input and a button for users to add items to the list.  As you saw above, you can create a local
    variable reference in your template with <code>#varname</code>.  Call it <code>#todotext</code> here.

  code-example(language="html").
    &lt;input #todotext&gt;
  p.
    Specify the target of the click event binding as your controller's
    <code>addTodo()</code> method and pass
    it the value. Since you created a reference called <code>todotext</code>,
    you can get the value with <code>todotext.value.</code>

  code-example(language="html").
    &lt;button (click)="addTodo(todotext.value)"&gt;Add Todo&lt;/button&gt;

  p.
    To make pressing Enter do something useful,
    you can add a keyup event handler to the input field.
    This event handler uses APIs defined in
    <a href="https://api.dartlang.org/apidocs/channels/stable/dartdoc-viewer/dart:html">dart:html</a>,
    so be sure to import that library.

  code-example(language="dart").
    import 'dart:html';
    ...

    // In the template:
    &lt;input #todotext (keyup)="doneTyping(\$event)"&gt;
    ...

    // In the component controller class:
    doneTyping(KeyboardEvent event) {
      if (event.keyCode == KeyCode.ENTER) {
        InputElement e = event.target;
        addTodo(e.value);
        e.value = null;
      }
    }

.l-main-section
  h2#section-final-code Final code

  code-tabs
    code-pane(language="dart" name="lib/todo_list.dart" format="linenums").
      library user_input.todo_list;

      import 'dart:html';
      import 'package:angular2/angular2.dart';

      @Component(selector: 'todo-list')
      @View(
          // An alternative to using \$event is to use a raw string instead.
          // For example, change "template: '''" to "template: r'''".
          template: '''
          &lt;ul&gt;
            &lt;li *ng-for="#todo of todos"&gt;
              {{ todo }}
            &lt;/li&gt;
          &lt;/ul&gt;

          &lt;input #todotext (keyup)="doneTyping(\$event)"&gt;
          &lt;button (click)="addTodo(todotext.value)"&gt;Add Todo&lt;/button&gt;
      ''', directives: const [NgFor])
      class TodoList {
        List&lt;String&gt; todos = [
          'Eat breakfast',
          'Walk dog',
          'Breathe',
          'Learn Angular'
        ];

        addTodo(String todo) {
          todos.add(todo);
        }

        doneTyping(KeyboardEvent event) {
          if (event.keyCode == KeyCode.ENTER) {
            InputElement e = event.target;
            addTodo(e.value);
            e.value = null;
          }
        }
      }
    code-pane(language="dart" name="web/main.dart" format="linenums").
      import 'package:angular2/bootstrap.dart';
      import 'package:user_input/todo_list.dart';

      main() {
        bootstrap(TodoList);
      }
    code-pane(language="html" name="web/index.html" format="linenums").
      &lt;!DOCTYPE html&gt;
      &lt;html&gt;
        &lt;head&gt;
          &lt;title&gt;User Input&lt;/title&gt;
          &lt;link rel=&quot;stylesheet&quot; href=&quot;style.css&quot;&gt;
          &lt;script async src=&quot;main.dart&quot; type=&quot;application/dart&quot;&gt;&lt;/script&gt;
          &lt;script async src=&quot;packages/browser/dart.js&quot;&gt;&lt;/script&gt;
        &lt;/head&gt;
        &lt;body&gt;
          &lt;todo-list&gt;&lt;/todo-list&gt;
        &lt;/body&gt;
      &lt;/html&gt;
    code-pane(language="yaml" name="pubspec.yaml" format="linenums").
      name: user_input
      description: User Input example
      version: 0.0.1
      dependencies:
        angular2: 2.0.0-alpha.45
        browser: ^0.10.0
      transformers:
      - angular2:
          entry_points: web/main.dart