通过经纬度计算俩点之间的距离
function distance(lat1,lon1,lat2,lon2) {//获取地图上俩个点之间的距离var R = 6378; // 地球半径 单位kmvar dLat = (lat2-lat1) * Math.PI / 180;var dLon = (lon2-lon1) * Math.PI / 180; var a = Math.sin(dLat/2) * Math.sin(dLat/2) +Math.cos(lat1 * Math.PI / 180 ) * Math.cos(lat2 * Math.PI / 180 ) * Math.sin(dLon/2) * Math.sin(dLon/2); var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a)); var d = R * c;return d;}