根據經緯度 算2點距離

//計算兩點位置距離
window.alert(getDistance(116.331398,39.897445,116.313098,39.8860000));
function getDistance(lat1, lng1, lat2, lng2) {

lat1 = lat1 || 0;

lng1 = lng1 || 0;

lat2 = lat2 || 0;

lng2 = lng2 || 0;

var rad1 = lat1 * Math.PI / 180.0;

var rad2 = lat2 * Math.PI / 180.0;

var a = rad1 - rad2;

var b = lng1 * Math.PI / 180.0 - lng2 * Math.PI / 180.0;

var r = 6378137; //地球半徑

var distance = r * 2 * Math.asin(Math.sqrt(Math.pow(Math.sin(a / 2), 2) + Math.cos(rad1) * Math.cos(rad2) * Math.pow(Math.sin(b / 2), 2)));

/*

if (distance > 1000){

distance = Math.round(distance / 1000);

}*/

 

return distance; }