title: Use of .map with http in Angular 2
body: <p>I want to know that do we really need <code>.map</code> when calling any api using <code>http</code> in <code>Angular 2</code>?<br><br>Please check my below code. It is working fine with <code>.map</code> and even without <code>.map</code>. If api returns data then it will return success else it will return error. I will also return any model data from here after performing some action. So, do I need <code>Observable</code> ? Is there any benefit of using it ? I am using <code>.subscribe</code> at <code>component</code> side to receive data. Is this fine or do I need any improvement ?</p>
  
  <pre><code>returnData: ReturnData;
  callyAPI(body: modelData) {
       return this.http.post(URL, body)
             .do(data =&gt; {
                  for (let i = 0; i &lt; data.length; ++i) {
                     this.returnData.push(data[i]);
                  }
                  return this.returnData;
              },
                 error =&gt; {});
        });
  }
  </code></pre>