title: Angular2 subscribe understand arrow function
body: <p>I try to understand arrow functions of typescript by the example of <strong>Angular 2</strong> Observable subscribe method. Could somebody explain me:</p>
  
  <p>I have this code which works:</p>
  
  <pre><code> this.readdataservice.getPost().subscribe(
              posts =&gt; { this.posts = posts; }
          );
  </code></pre>
  
  <p>but should it be the same if I use this? But this doesn't work.</p>
  
  <pre><code>this.readdataservice.getPost().subscribe(
              function (posts) {
                  this.posts = posts;
              }
  
          );
  </code></pre>