获取两个经纬度间距离

// 获取两个经纬度的距离 (km)
getDistance(long1,lat1,long2,lat2) {
var earth_radius = 6378.137;
var a,b,distance,sa2,sb2;
lat1 = this.rad(lat1);
lat2 = this.rad(lat2);
a = lat1-lat2;
// b = this.rad(long1-long2);
b = this.rad(long1)-this.rad(long2);
sa2 = Math.sin(a/2.0);
sb2 = Math.sin(b/2.0);
distance = 2earth_radiusMath.asin(Math.sqrt(sa2 * sa2 + Math.cos(lat1)
* Math.cos(lat2)sb2sb2));
return distance;
}

rad(x){
    return x*Math.PI/180.0;
}

// 适用于近距离
GetShortDistance(lon1,lat1,lon2,lat2) {
var DEF_PI = 3.14159265359; // PI
var DEF_2PI= 6.28318530712; // 2*PI
var DEF_PI180= 0.01745329252; // PI/180.0
var DEF_R =6370693.5; // radius of earth

var ew1,ns1,ew2,ns2;
var dx,dy,dew;
var distance;
// 角度转换为弧度
ew1 = lon1 * DEF_PI180;
ns1 = lat1 * DEF_PI180;
ew2 = lon2 * DEF_PI180;
ns2 = lat2 * DEF_PI180;
// 经度差
dew = ew1 - ew2;
// 若跨东经和西经180 度，进行调整
if (dew > DEF_PI)
dew = DEF_2PI - dew;
else if (dew < -DEF_PI)
dew = DEF_2PI + dew;
dx = DEF_R * Math.cos(ns1) * dew; // 东西方向长度(在纬度圈上的投影长度)
dy = DEF_R * (ns1 - ns2); // 南北方向长度(在经度圈上的投影长度)
// 勾股定理求斜边长
distance = Math.sqrt(dx * dx + dy * dy);
return distance;

}

// 适用于远距离
GetLongDistance(lon1,lat1,lon2,lat2)
{
var DEF_PI = 3.14159265359; // PI
var DEF_2PI= 6.28318530712; // 2*PI
var DEF_PI180= 0.01745329252; // PI/180.0
var DEF_R =6370693.5; // radius of earth

var ew1, ns1, ew2, ns2;
var distance;
// 角度转换为弧度
ew1 = lon1 * DEF_PI180;
ns1 = lat1 * DEF_PI180;
ew2 = lon2 * DEF_PI180;
ns2 = lat2 * DEF_PI180;
// 求大圆劣弧与球心所夹的角(弧度)
distance = Math.sin(ns1) * Math.sin(ns2) + Math.cos(ns1) * Math.cos(ns2) * Math.cos(ew1 - ew2);
// 调整到[-1..1]范围内，避免溢出
if (distance > 1.0)
    distance = 1.0;
else if (distance < -1.0)
    distance = -1.0;
// 求大圆劣弧长度
distance = DEF_R * Math.acos(distance);
return distance;

}