WGS84轉百度坐標

function GetDistance(lat1, lng1, lat2, lng2) {
var radLat1 = lat1 * Math.PI / 180.0;
var radLat2 = lat2 * Math.PI / 180.0;
var a = radLat1 - radLat2;
var b = lng1 * Math.PI / 180.0 - lng2 * Math.PI / 180.0;
var s = 2 * Math.asin(Math.sqrt(Math.pow(Math.sin(a / 2), 2) +
Math.cos(radLat1) * Math.cos(radLat2) * Math.pow(Math.sin(b / 2), 2)));
s = s * 6378.137; // EARTH_RADIUS;
s = Math.round(s * 10000) / 10000;
return s;
}