js根据经纬度计算两地距离

废话不多说,上代码

function countDist(lat1, lng1, lat2, lng2) {//纬度1,经度1,纬度2,经度2

    var f = ((lat1 + lat2) / 2) * Math.PI / 180.0;

    var g = ((lat1 - lat2) / 2) * Math.PI / 180.0;

    var l = ((lng1 - lng2) / 2) * Math.PI / 180.0;

    var sg = Math.sin(g);

    var sl = Math.sin(l);

    var sf = Math.sin(f);

    var s, c, w, r, d, h1, h2;

    var a = 6378137.0;//地球的直径

    var fl = 1 / 298.257;

    sg = sg * sg;

    sl = sl * sl;

    sf = sf * sf;

    s = sg * (1 - sl) + (1 - sf) * sl;

    c = (1 - sg) * (1 - sl) + sf * sl;

    w = Math.atan(Math.sqrt(s / c));

    r = Math.sqrt(s * c) / w;

    d = 2 * w * a;

    h1 = (3 * r - 1) / 2 / c;

    h2 = (3 * r + 1) / 2 / s;

    var num = d * (1 + fl * (h1 * sf * (1 - sg) - h2 * (1 - sf) * sg))

    return num;//返回单位:米

}