javascript - Scope variables in typescript

the reason why google maps is not defined there, is because it is the callback of a function, which makes 'this' not equal to the page anymore, putting it in a variable will fix the issue.

  private siteForm: FormGroup;

  loadMap(){

  var siteformFromPage=this.siteForm; //this should work
        google.maps.event.addListener(marker, 'dragend', function(marker, siteForm){
        let newlatLng = marker.latLng; 
        console.log(siteformFromPage);
      });
  }

EDIT: if you want the latest value, you could also try is this way:

  private siteForm: FormGroup;

  loadMap(){
       var that=this; //cache that value of the page.

        google.maps.event.addListener(marker, 'dragend', function(marker, siteForm){
        let newlatLng = marker.latLng; 
        console.log(that.siteformFromPage);
      });
  }