1. function getDistance(lat1, lng1, lat2, lng2) {
    2.   var dis = 0;
    3.   var radLat1 = toRadians(lat1);
    4.   var radLat2 = toRadians(lat2);
    5.   var deltaLat = radLat1 - radLat2;
    6.   var deltaLng = toRadians(lng1) - toRadians(lng2);
    7.   var dis = 2 * Math.asin(Math.sqrt(Math.pow(Math.sin(deltaLat / 2), 2) + Math.cos(radLat1) * Math.cos(radLat2) * Math.pow(Math.sin(deltaLng / 2), 2)));
    8.   return dis * 6378137;
    10.   function toRadians(d) {
    11.     return d * Math.PI / 180;
    12.   }
    13. }

    返回的距离单位为米