Question

Ok so i have a map with some markers on it. There is a click event on the map that should get the closest marker however when the find_closest_marker(event) function runs it breaks on the map.markers.length saying that its undefined.

Here is a link to what im trying to http://jsfiddle.net/VyzFq/7/

Can anyone can please show me where I’m going wrong here.

Answer 1

Looks like there are a couple of problems:

1) the map.markers array hasn’t been declared. declare it above the for loop, and push the markers onto the markers array.

...
var infowindow = new google.maps.InfoWindow();

var marker, i;
map.markers = []; // ADD THIS LINE
for (i = 0; i < locations.length; i++) {  
    marker = new google.maps.Marker({
        position: new google.maps.LatLng(locations[i][1], locations[i][2]),
        map: map
    });
    map.markers.push(marker); // ADD THIS LINE
...

2) the find_closest_point function can’t see the map variable. move the find_closest_point function to the scope where you are adding the click event listener:

// CHANGE THIS LINE
google.maps.event.addListener(map, 'click', find_closest_marker);

// TO:

google.maps.event.addListener(map, 'click', function( event ) {
    var lat = event.latLng.lat();
    var lng = event.latLng.lng();
    var R = 6371;
    var distances = [];
    var closest = -1;
    for( i=0;i<map.markers.length; i++ ) {
        var mlat = map.markers[i].position.lat();
        var mlng = map.markers[i].position.lng();
        var dLat  = rad(mlat - lat);
        var dLong = rad(mlng - lng);
        var a = Math.sin(dLat/2) * Math.sin(dLat/2) +
            Math.cos(rad(lat)) * Math.cos(rad(lat)) * Math.sin(dLong/2) * Math.sin(dLong/2);
        var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
        var d = R * c;
        distances[i] = d;
        if ( closest == -1 || d < distances[closest] ) {
            closest = i;
        }
    }

    alert(map.markers[closest].title);
});