title: Angular wait for multiple http requests to complete and then fire the last one
body: <p>I have 4 http requests. Three receives lookup values while the 4th one gets actual form data.</p>
  
  <p>They go like this:</p>
  
  <pre><code>   let medicalData = this.data.getCodes('medical').subscribe((data: {}) =&gt; {
       console.log('med');
         this.Medical = data;
          });
     let delayData = this.data.getCodes('delay').subscribe((data: {}) =&gt; {
      console.log('del');
            this.Delays = data;
             });
     let disabilityData = this.data.getCodes('disability').subscribe((data: {}) =&gt; {
      console.log('dis');
              this.Disability = data;
               });
     let districtData = this.data.getCodes('district').subscribe((data: {}) =&gt; {
      console.log('dist');
                this.District = data;
                 });
  </code></pre>
  
  <p>How can I make the 4th get request wait till the first three requests are complete ?</p>
  
  <p>Thanks in advance</p>