.statement
h4 Live Examples
p.
If you want to skip to the working examples you can check out these links on Plunker. TypeScript Example or ES5 Example.
.l-main-section
h2#section-responding-to-user-input Responding to user input with event syntax
p.
You can make your application respond to user input by using the event syntax. The event syntax starts with an event name surrounded by parenthesis: (event). A controller function is then assigned to the event name: (event)="controllerFn()".
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.
<input (keyup)="myControllerMethod()">
h3#local-variables Local variables
p.
As in previous examples, you can make element references available to other parts of the template as a local
variable using the #var syntax. With this and events, we can do the old "update text as you type" example:
pre.prettyprint.lang-html
code.
<input #myname (keyup)>
<p>{{myname.value}}</p>
p.text-body(ng-non-bindable).
The #myname creates a local variable in the template that we'll refer to below in the
<p> element. The (keyup) tells Angular to trigger updates when it gets a keyup
event. And the {{myname.value}} binds the text node of the <p> 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:
figure.image-display
img(src='user-input-example1.png')
.l-ain-section
h2#section-create-an-array-property Create an array property
p.
With the default bootstrapping in place, create a controller class that will manage interactions with the
list. Inside the controller, add an array with an initial list of items. Then add a method that pushes new items
on the array when called.
.code-box
pre.prettyprint.linenums.lang-javascript(data-name="es5")
code.
//ES5
function TodoList() {
this.todos = ["Eat Breakfast", "Walk Dog", "Breathe"];
this.addTodo = function(todo) {
this.todos.push(todo);
};
}
pre.prettyprint.linenums.lang-typescript(data-name="typescript")
code.
//TypeScript
class TodoList {
todos: Array<string>
constructor() {
this.todos = ["Eat Breakfast", "Walk Dog", "Breathe"];
}
addTodo(todo: string) {
this.todos.push(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 TodoList. 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 *for iterator, create an <li> for each item in the todos array and set
its text to the value.
pre.prettyprint.linenums.lang-html
code.
<ul>
<li *for="#todo of todos">
{{ todo }}
</li>
</ul>
.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 #varname. Call it #todotext here.
pre.prettyprint.lang-html
code.
<input #todotext>
p.
Lastly, specify the target of the click event binding as your controller's addTodo() method and pass
it the value. Since you created a reference called todotext, you can get the value with
todotext.value.
pre.prettyprint.lang-html
code.
<button (click)="addTodo(todotext.value)">Add Todo</button>
p And then create the doneTyping() method on TodoList and handle adding the todo text.
pre.prettyprint.lang-javascript
code.
doneTyping($event) {
if($event.which === 13) {
this.addTodo($event.target.value);
$event.target.value = null;
}
}
.l-main-section
h2#section-final-code Final Code
.code-box
pre.prettyprint.lang-javascript(data-name="es5")
code.
//ES5
function TodoList() {
this.todos = ["Eat Breakfast", "Walk Dog", "Breathe"];
this.addTodo = function(todo) {
this.todos.push(todo);
};
this.doneTyping = function($event) {
if($event.which === 13) {
this.addTodo($event.target.value);
$event.target.value = null;
}
}
}
TodoList.annotations = [
new angular.Component({
selector: "todo-list"
}),
new angular.View({
template:
'<ul>' +
'<li *for="#todo of todos">' +
'{{ todo }}' +
'</li>' +
'</ul>' +
'<input #textbox (keyup)="doneTyping($event)">' +
'<button (click)="addTodo(textbox.value)">Add Todo</button>',
directives: [angular.For, angular.If]
})
];
document.addEventListener("DOMContentLoaded", function() {
angular.bootstrap(TodoList);
});
pre.prettyprint.lang-typescript(data-name="typescript")
code.
//TypeScript
import {Component, View, bootstrap, For, If} from 'angular2/angular2';
@Component({
selector: 'todo-list'
})
@View({
template: `
<ul>
<li *for="#todo of todos">
{{ todo }}
</li>
</ul>
<input #todotext (keyup)="doneTyping($event)">
<button (click)="addTodo(todotext.value)">Add Todo</button>
`,
directives: [For, If]
})
class TodoList {
todos: Array;
constructor() {
this.todos = ["Eat Breakfast", "Walk Dog", "Breathe"];
}
addTodo(todo: string) {
this.todos.push(todo);
}
doneTyping($event) {
if($event.which === 13) {
this.addTodo($event.target.value);
$event.target.value = null;
}
}
}
bootstrap(TodoList);