Using Google Maps: a custom javascript function returning undefined

Question

I'm trying to return the variable coord from GetLocation, but it only returns undefined. Any help appreciated!

var coord = "";
function GetLocation(address) {

    var geocoder = new google.maps.Geocoder();

    geocoder.geocode( { "address": address }, function (results, status) {

        if (status == google.maps.GeocoderStatus.OK) {
            coord = ParseLocation(results[0].geometry.location);

            // This alert shows the proper coordinates 
            alert(coord);
        }
        else{ }

    });

    // this alert is undefined
    alert(coord);
    return coord;
}

function ParseLocation(location) {

    var lat = location.lat().toString().substr(0, 12);
    var lng = location.lng().toString().substr(0, 12);

    return lat+","+lng;
}

Does geocode() execute asynchronously? If so, coord value is not yet know at the time the function returns. — Michael Berkowski
– Michael Berkowski, Commented Aug 23, 2012 at 19:36

Esailija · Accepted Answer · 2012-08-23 19:38:40Z

2

When you are returning coords from the outer function it is still in fact undefined. The inner function executes later when the asynchronous operation (if it wasn't asynchronous, the API would just give the result to you normally) is done.

Try passing a callback:

function GetLocation(address, cb) {

    var geocoder = new google.maps.Geocoder();

    geocoder.geocode( { "address": address }, function (results, status) {

        if (status == google.maps.GeocoderStatus.OK) {
            cb(ParseLocation(results[0].geometry.location));
        }
        else{ }

    });
}

You can then use it like so:

GetLocation( "asd", function(coord){
    alert(coord);
});

answered Aug 23, 2012 at 19:38

Esailija

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3 Comments

kylex Over a year ago

Ultimately I want to return the value from the function. yet if I do something like this var test = GetLocation( "asd", function(coord){ return coord; }); I don't think it'll work will it?

Esailija Over a year ago

No you cannot do it, this is why it takes a function in the first place. If you could do that, they would just return it normally. Duh, right? :P You cannot get far with javascript if you just treat it as a linear sequence of commands anyway. Events, XHR requests etc are all asynchronous.

kylex Over a year ago

Got it, was just hoping there would be a way around it. Ta!

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