title: RxJs Observable<string> vs Observable<string[]>
body: <p>I'm having a hard time getting my head around RxJS Observables, though I've used the observable pattern in a number of different situations throughout my life. Here's some code:</p>
  
  <pre><code>    const observable: Observable&lt;Response&gt; = createdElswhere();
      let test1: Observable&lt;string&gt;;
      let test2: Observable&lt;string[]&gt;;
  
      test1 = observable.map(r =&gt; r.json());
      test2 = observable.map(r =&gt; r.json());
  </code></pre>
  
  <p>Response.json() returns an array of data - usually objects that will be mapped to a typescript object, but they're just strings in this case:</p>
  
  <pre><code>[  
      "test1",
      "test2",
      "test3",
      "test4"
  ]
  </code></pre>
  
  <p>When I subscribe to the <code>test1</code> or <code>test2</code> properties (in an angular view template, or manually in code using <code>.subscribe()</code> for example), the observable generic type doesn't seem to make any difference to the framework. The items are displayed exactly the same, even though the 'data' inside the observable is different (one is an array, the other is an array of observable strings).</p>
  
  <p>Can anyone explain the difference between <code>Observable&lt;string&gt;</code> and <code>Observable&lt;string[]&gt;</code>, and give me an example of how they <em>should</em> be used?</p>