Javascript计算两个marker之间的距离(Google Map V3)

var oldMarker = new google.maps.Marker({
position: new google.maps.LatLng("31.95678", "177.898673"),
map: map,
title:"old"
});
var newMarker = new google.maps.Marker({
position: new google.maps.LatLng("31.45678", "177.098673"),
map: map,
title:"new"
});

<script type="text/javascript" src="http://maps.googleapis.com/maps/api/js?sensor=false&libraries=geometry"></script>

var meters = google.maps.geometry.spherical.computeDistanceBetween(oldMarker.getPosition(), newMarker.getPosition());
document.getElementById("distance").innerText = meters+"米";