在javascript中设置内部作用域的外部作用域变量

Question

var lat = 0.0;
var lng = 0.0;
var jsonData = null;
var geocoder = new google.maps.Geocoder();
var miles = $('#milesAway').val();

// find what the user is locating by
if ($('#zipCode').is(':visible'))
{
    var zipText = $('#zipCode').val();
    if (isValidUSZip(zipText))
    {
        geocoder.geocode( {
            'address': zipText
        }, function(results, status) {
            if (status == google.maps.GeocoderStatus.OK) {
                lat = results[0].geometry.location.lat();
                lng = results[0].geometry.location.lng();
                map.setCenter(results[0].geometry.location);
            } else {
                alert("Zip Code couldn't be located.");
            }
        });
    }
    else
    {
        alert('Please enter a valid US zip code.');
    }
}

lat and lng are still set as 0.0 after this thing runs through, why? Shouldn't I be able to set these like this?

Edit: I get to the point where they are supposed to be set too, if I put an alert there I can see the values that they are supposed to be set to.

Answer 1

The geocoder.geocode callback isn't running immediately, it's delayed until the AJAX call comes back. There's nothing wrong with the scope, the variables just won't be changed until the XHR is done.

If you're depending on them being changed, try putting your dependent code (or a call to a function) within the geocoder callback function.