Js算两经纬度间球面距离

function GetDistance( lat1, ?lng1, ?lat2, ?lng2){ ???var radLat1 = lat1 * Math.PI / 180.0 ???var radLat2 = lat2 * Math.PI / 180.0 ???var a = (lat1 - lat2) * Math.PI / 180.0; ???var b = (lng1 - 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 * 6378137 ;// EARTH_RADIUS; ???s = Math.round(s * 10000) / 10000; ???return s;}