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

.l-main-section
  p.
    You can make your application respond to user input by associating events with functions in your controller
    using the event syntax using <strong>()</strong> to surround the name of an event.
  p.
    For a particular control like an input you can have it call methods on your controller on keyup event like so:

  pre.prettyprint.lang-html
    code.
      &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 # syntax.  With this and events, we can do the old "update text as you type" example:

  pre.prettyprint.lang-html
    code.
      &lt;input #my-name (keyup)&gt;
      &lt;p&gt;{{my-name.value}}&lt;/p&gt;

  p.text-body(ng-non-bindable).
    The <code>#my-name</code> creates a local variable in the template that we'll refer to below in the
    <code>&lt;p&gt;</code> element.  The <code>(keyup)</code> tells Angular to trigger updates when it gets a keyup
    event.  And the <code>{{my-name.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 users enter items and add them to a list like this:
  div(align='center')
      img(src='user-input-example1.png')


.l-main-section
  h2#section-create-an-array-property Create an array property
  p.
    With the default bootstrapping in place, create a TodoController class that will manage interactions with the
    list. Inside TodoController, add an array with an initial list of items.  Then add a method that pushes new items
    on the array when called.

  pre.prettyprint.linenums.lang-dart
    code.
      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 with the previous example, in a production application you will separate your model out into another class
      and inject it into <code>TodoController</code>.  We've omitted it here for brevity.

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

  pre.prettyprint.linenums.lang-html
    code.
      &lt;ul&gt;
         &lt;li *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.

  pre.prettyprint.lang-html
    code.
      &lt;input #todotext&gt;
  p.
    Lastly, 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>

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

  p And then create the doneTyping() method on TodoList and handle adding the todo text.

  pre.prettyprint.lang-dart
    code.
      doneTyping(KeyboardEvent event) {
         if (event.which == 13) {
           InputElement e = event.target;
           addTodo(e.value);
           e.value = null;
         }
       }

.l-main-section
  h2#section-final-code Final Code
  p Here's the final <code>todo_list.dart</code>
  pre.prettyprint.lang-dart
    code.
      part of user_input;

      @Component(
        selector: 'todo-list'
      )
      @View(
        // Without r before ''' (a raw string), $event breaks Angular!
        // An alternative is to use \$event instead.
        template: '''
          &lt;ul&gt;
            &lt;li *for=&quot;#todo of todos&quot;&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[For]
         )
         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.which == 13) {
               InputElement e = event.target;
               addTodo(e.value);
               e.value = null;
             }
           }
         }