angular2 How to select all？ : <pre><code>class Heroe{
    selected ?: boolean;
}    


heroes: Observable&lt;Heroe[]&gt;
....
this.heroes = this.heroService.getHeroes()
....
select_all(){
    How to do it?
}
</code></pre>

<p>=======</p>

<pre><code>&lt;div *ngFor="let hero of heroes | async" &gt;
  &lt;span *ngIF="hero.selected"&gt;selected&lt;/span&gt;
  {{hero.name}}
&lt;/div&gt;
&lt;input type="checkbox" #checkbox (change)="select_all(checkbox.checked)"&gt;
</code></pre>

<p><strong>How to select？</strong>
<strong>How to select？</strong>
<strong>How to select？</strong>
<strong>How to select？</strong>
<strong>How to select？</strong>
<strong>How to select？</strong></p>
