title: ionic2 TypeScript shows error: Cannot find name 'google' and '$', but google map and jquery still works
body: <p>I am trying to build a ionic2 application using TypeScript.</p>
  
  <p>In index.html, I've tried to plug the jquery and google map JS API into it before cordova.js:</p>
  
  <pre><code>  &lt;!-- Vendor --&gt;
    &lt;script src="https://maps.googleapis.com/maps/api/js?key=XXXXX&amp;signed_in=false"&gt;&lt;/script&gt;
    &lt;script src="asset/jquery.min.js"&gt;&lt;/script&gt;
  
    &lt;!-- cordova.js required for cordova apps --&gt;
    &lt;script src="cordova.js"&gt;&lt;/script&gt;
  </code></pre>
  
  <p>The google map and jquery inside the app is working normally, however just wondering why these error messages shows when I run "ionic serve" command</p>
  
  <pre><code>TypeScript error: /Users/xxx/client_app/app/pages/step1/step1.ts(15,21): Error TS2304: Cannot find name 'google'.
  TypeScript error: /Users/xxx/client_app/app/pages/step1/step1.ts(30,18): Error TS2304: Cannot find name 'google'.
  TypeScript error: /Users/xxx/client_app/app/pages/step1/step1.ts(37,24): Error TS2304: Cannot find name 'google'.
  TypeScript error: /Users/xxx/client_app/app/pages/step1/step1.ts(39,5): Error TS2304: Cannot find name '$'.
  TypeScript error: /Users/xxx/client_app/app/pages/step1/step1.ts(39,42): Error TS2304: Cannot find name '$'.
  TypeScript error: /Users/xxx/client_app/app/pages/step1/step1.ts(39,76): Error TS2304: Cannot find name '$'.
  </code></pre>
  
  <p>Here are part of my code in step1.ts:</p>
  
  <pre><code>  ngOnInit() {
      this.gmap = new google.maps.Map(document.getElementById('gmap_canvas'), {
              center: {
                  lat: 22.280102,
                  lng: 114.183751
              },
              zoom: 16,
              streetViewControl: false,
              styles : [{
                  featureType: "poi",
                  elementType: "labels",
                  stylers: [
                      { visibility: "off" }
                  ]
              }],
              mapTypeControlOptions: {
                  mapTypeIds: [google.maps.MapTypeId.ROADMAP]
              },
              overviewMapControl: false,
              mapTypeControl: false,
          });
  
      this.gmap.controls[google.maps.ControlPosition.TOP_CENTER].push(document.getElementById('gmep_center_marker'));
  
      $('#gmep_center_marker').css({ top: ($('#gmap_canvas').height() / 2) - $('#gmep_center_marker').height() });
    }
  </code></pre>