已知A点经纬度坐标，方位角角度，距离，求B点经纬度

/**
 * 度换成弧度
 * @param  {Float} d  度
 * @return {[Float}   弧度
 */
LIB.rad = function (d) {
  return d * Math.PI / 180.0;
}

/**
 * 弧度换成度
 * @param  {Float} x 弧度
 * @return {Float}   度
 */
LIB.deg = function (x) {
  return x * 180 / Math.PI;
}

 this.ADestinceAngle_B = function (lonlat, brng, dist) {
    var u = this;
    var ct = {
      a: 6378137,
      b: 6356752.3142,
      f: 1 / 298.257223563
    };
    var a = ct.a, b = ct.b, f = ct.f;

    var lon1 = lonlat.lon * 1;  //乘一（*1）是为了确保经纬度的数据类型为number
    var lat1 = lonlat.lat * 1;

    var s = dist;
    var alpha1 = LIB.rad(brng);
    var sinAlpha1 = Math.sin(alpha1);
    var cosAlpha1 = Math.cos(alpha1);

    var tanU1 = (1 - f) * Math.tan(LIB.rad(lat1));
    var cosU1 = 1 / Math.sqrt((1 + tanU1 * tanU1)), sinU1 = tanU1 * cosU1;
    var sigma1 = Math.atan2(tanU1, cosAlpha1);
    var sinAlpha = cosU1 * sinAlpha1;
    var cosSqAlpha = 1 - sinAlpha * sinAlpha;
    var uSq = cosSqAlpha * (a * a - b * b) / (b * b);
    var A = 1 + uSq / 16384 * (4096 + uSq * (-768 + uSq * (320 - 175 * uSq)));
    var B = uSq / 1024 * (256 + uSq * (-128 + uSq * (74 - 47 * uSq)));

    var sigma = s / (b * A), sigmaP = 2 * Math.PI;
    while (Math.abs(sigma - sigmaP) > 1e-12) {
      var cos2SigmaM = Math.cos(2 * sigma1 + sigma);
      var sinSigma = Math.sin(sigma);
      var cosSigma = Math.cos(sigma);
      var deltaSigma = B * sinSigma * (cos2SigmaM + B / 4 * (cosSigma * (-1 + 2 * cos2SigmaM * cos2SigmaM) -
        B / 6 * cos2SigmaM * (-3 + 4 * sinSigma * sinSigma) * (-3 + 4 * cos2SigmaM * cos2SigmaM)));
      sigmaP = sigma;
      sigma = s / (b * A) + deltaSigma;
    }

    var tmp = sinU1 * sinSigma - cosU1 * cosSigma * cosAlpha1;
    var lat2 = Math.atan2(sinU1 * cosSigma + cosU1 * sinSigma * cosAlpha1,
      (1 - f) * Math.sqrt(sinAlpha * sinAlpha + tmp * tmp));
    var lambda = Math.atan2(sinSigma * sinAlpha1, cosU1 * cosSigma - sinU1 * sinSigma * cosAlpha1);
    var C = f / 16 * cosSqAlpha * (4 + f * (4 - 3 * cosSqAlpha));
    var L = lambda - (1 - C) * f * sinAlpha *
      (sigma + C * sinSigma * (cos2SigmaM + C * cosSigma * (-1 + 2 * cos2SigmaM * cos2SigmaM)));
    var revAz = Math.atan2(sinAlpha, -tmp);  // final bearing
    var lon_destina = lon1 * 1 + LIB.deg(L);
    var lonlat_destination = {lon: lon_destina, lat: LIB.deg(lat2)};

    return lonlat_destination;
  }

已知起点坐标lon：114,lat：38

正北夹角45度

长度距离100米

调用：

 var coord = this.ADestinceAngle_B({lon:114,lat:38},45,100)