WGS84坐标转换GCJ02坐标 JS实现

var pi = 3.14159265358979324;
var a = 6378245.0;
var ee = 0.00669342162296594323;

/**
* WGS84坐标转换GCJ02坐标
* @param wgLat：wgs纬度
* @param wgLon：wgs经度
* @return Array[lat:gcj纬度,lon:gcj经度]
*/
load_map.wgs84togcj02 = function (wgLat, wgLon){
var mgLat, mgLon;
if (load_map.outOfChina(wgLat, wgLon)){
mgLat = wgLat;
mgLon = wgLon;
return;
}
var dLat = load_map.transformLat(wgLon - 105.0, wgLat - 35.0);
var dLon = load_map.transformLon(wgLon - 105.0, wgLat - 35.0);
var radLat = wgLat / 180.0 * pi;
var magic = Math.sin(radLat);
magic = 1 - ee * magic * magic;
var sqrtMagic = Math.sqrt(magic);
dLat = (dLat * 180.0) / ((a * (1 - ee)) / (magic * sqrtMagic) * pi);
dLon = (dLon * 180.0) / (a / sqrtMagic * Math.cos(radLat) * pi);
mgLat = wgLat + dLat;
mgLon = wgLon + dLon;
var arr = {};
arr['lat'] = mgLat;
arr['lon'] = mgLon;
return arr;
}
load_map.outOfChina = function(lat,lon) {
if (lon < 72.004 || lon > 137.8347)
return true;
if (lat < 0.8293 || lat > 55.8271)
return true;
return false;
}
load_map.transformLat = function(x, y){
var ret = -100.0 + 2.0 * x + 3.0 * y + 0.2 * y * y + 0.1 * x * y + 0.2 * Math.sqrt(Math.abs(x));
ret += (20.0 * Math.sin(6.0 * x * pi) + 20.0 * Math.sin(2.0 * x * pi)) * 2.0 / 3.0;
ret += (20.0 * Math.sin(y * pi) + 40.0 * Math.sin(y / 3.0 * pi)) * 2.0 / 3.0;
ret += (160.0 * Math.sin(y / 12.0 * pi) + 320 * Math.sin(y * pi / 30.0)) * 2.0 / 3.0;
return ret;
}
load_map.transformLon = function(x, y){
var ret = 300.0 + x + 2.0 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * Math.sqrt(Math.abs(x));
ret += (20.0 * Math.sin(6.0 * x * pi) + 20.0 * Math.sin(2.0 * x * pi)) * 2.0 / 3.0;
ret += (20.0 * Math.sin(x * pi) + 40.0 * Math.sin(x / 3.0 * pi)) * 2.0 / 3.0;
ret += (150.0 * Math.sin(x / 12.0 * pi) + 300.0 * Math.sin(x / 30.0 * pi)) * 2.0 / 3.0;
return ret;
}