The order of execution of codes in javascript - navigator.geolocation

Question

So I was having problem with getting the longitude and latitude using the navigator.geolocation and storing it in a global variable. I used alerts at different places to check the flow of the javascript code. I found that the order to be 1, 2, 4 and 3. Why is that? I am really confused.

 $(document).ready( function() {
      var latitude;
      var longitude;
      alert('1');
      if(navigator.geolocation){
        alert('2');
            navigator.geolocation.getCurrentPosition( function(position){
              alert('3');
              latitude = position.coords.latitude;
              longitude = position.coords.longitude;
              geoCoords(latitude, longitude);


            });
         }

      alert('4');

    });

So that means there is no need to put it into a global variable? — DazedNConfused, Jan 27 '17 at 01:13
see http://stackoverflow.com/questions/14220321/how-do-i-return-the-response-from-an-asynchronous-call — Jaromanda X, Jan 27 '17 at 01:17

score 3 · Accepted Answer · answered Jan 27 '17 at 01:19

navigator.geolocation.getCurrentPosition is asynchronous - the function you pass into it as an argument is the callback function, which executes after getCurrentPosition has completed successfully. From the Mozilla docs:

navigator.geolocation.getCurrentPosition(success[, error[, options]])

The rest of the javascript code outside of the callback function will continue to execute without waiting for the callback function to run, which is why you see the order of 1, 2, 4, 3.

The order of execution of codes in javascript - navigator.geolocation

1 Answers1