Returning json array from a function to a variable

Question

I am developing a script to get the latlng from google maps by the address.

If I put an alert(jsonarr.lat); inside the function map_address() I get the correct value, but if I assign the result to a variable like this:

var coord = map_address('address');

alert(coord.lat);

I get the error coord is undefined

function map_address(addr)
    {

        var input_address = addr;
        var geocoder = new google.maps.Geocoder();
        geocoder.geocode( { address: input_address }, function(results, status) {
            if (status == google.maps.GeocoderStatus.OK) {
                var lat = results[0].geometry.location.lat();
                var lng = results[0].geometry.location.lng();


                      jsonarr={'lat':lat,'lng':lng}
                      alert(jsonarr.lat);
                      return jsonarr;           
            } else {
                alert("Nessuna coordinata trovata da questo indirizzo!");
            }
        });
    }

You can't return from there, it's an asynchronous callback.

bfavaretto
– bfavaretto

2012-11-22 17:10:28 +00:00
Commented Nov 22, 2012 at 17:10 — bfavaretto
– bfavaretto, Commented Nov 22, 2012 at 17:10

wf9a5m75 · Accepted Answer · 2012-11-22 17:13:11Z

1

Try like this:

function map_address(addr, callback) {

    var input_address = addr;
    var geocoder = new google.maps.Geocoder();
    geocoder.geocode( { address: input_address }, function(results, status) {
        if (status == google.maps.GeocoderStatus.OK) {
            var lat = results[0].geometry.location.lat();
            var lng = results[0].geometry.location.lng();


                               jsonarr={'lat':lat,'lng':lng}
                               alert(jsonarr.lat);
                               callback(jsonarr) ;


                            }
        else {
            alert("Nessuna coordinata trovata da questo indirizzo!");
            }
        });
}
map_address("hogehoge", function(result){
  alert(result)
});

answered Nov 22, 2012 at 17:13

wf9a5m75

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Comments

Christian Westman · Accepted Answer · 2012-11-22 17:15:59Z

1

the geocoder.geocode(..); function is asynchronous as it wraps another function inside that will be called later when the geocode operation is done.

because of this map_address(...) will always return undefined

edited Nov 22, 2012 at 17:15

answered Nov 22, 2012 at 17:10

Christian Westman

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Comments

Luca · Accepted Answer · 2012-11-23 09:24:34Z

Thanks all for the answers, i put all my code inside the callback and all work fine this is the final code.

   function map_address(addr,callback)
        {

            var input_address = addr;
            var geocoder = new google.maps.Geocoder();
            geocoder.geocode( { address: input_address }, function(results, status) {
                if (status == google.maps.GeocoderStatus.OK) 
                {
                    var lat = results[0].geometry.location.lat();
                    var lng = results[0].geometry.location.lng();

                    jsonarr={'lat':lat,'lng':lng}                       
                    return callback(jsonarr);                        
                }
                else {
                    alert("No coord find");
                }
            });
        }


$(document).ready(function(){ 
   $(window).load(function(){ 

map_address('address string',function(coord){


  var center=new google.maps.LatLng(coord.lat,coord.lng);



  var settings = {
          zoom: 16,
          center: center,
          mapTypeControl: false,
          mapTypeControlOptions: {style: google.maps.MapTypeControlStyle.DROPDOWN_MENU},
          navigationControl: true,
          navigationControlOptions: {style: google.maps.NavigationControlStyle.SMALL},
          mapTypeId: google.maps.MapTypeId.ROADMAP
      }; 

  var map=new google.maps.Map(document.getElementById("map"), settings);

var marker = new google.maps.Marker({
position: new google.maps.LatLng(coord.lat,coord.lng),
map: map
});


});
});

});

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