投影坐标（XY)坐标转换成地理坐标（经纬度）

//示例 EPSG3857 转 WGS84var firstProjection = new proj4.Proj("EPSG:3857");var secondProjection = new proj4.Proj("EPSG:4326");var result = proj4.transform(firstProjection, secondProjection,[12697455.33850049, 2576232.94688235]); //返回对象{x:x,y:y}//换一种写法，直接使用EPSG编号，如果某个EPSG内置不支持，需要先进行定义proj4("EPSG:3857","EPSG:4326",[12697455.33850049, 2576232.94688235]) //返回数组 [114.06318200000003, 22.537922000000027]