你在小程序中怎么计算两个经纬度的距离？

// 方法定义 lat,lng 
function GetDistance( lat1,  lng1,  lat2,  lng2){
        var radLat1 = lat1*Math.PI / 180.0;
    var radLat2 = lat2*Math.PI / 180.0;
    var a = radLat1 - radLat2;
    var  b = lng1*Math.PI / 180.0 - lng2*Math.PI / 180.0;
        var s = 2 * Math.asin(Math.sqrt(Math.pow(Math.sin(a/2),2) +
        Math.cos(radLat1)*Math.cos(radLat2)*Math.pow(Math.sin(b/2),2)));
            s = s *6378.137 ;// EARTH_RADIUS;
            s = Math.round(s * 10000) / 10000;
                return s;
    }
    // 调用 return的距离单位为km
    console.log(GetDistance(22.54605355,114.02597366,22.620315,114.144802));

var QQMapWX = require('../../mapsdk/qqmap-wx-jssdk.js');
var qqmapsdk;
const app = getApp();
Page({

  /**
   * 页面的初始数据
   */
  data: {
  
  lat_dest:'目标纬度',
  lng_dest:'目标经度',
  location_info:{},
 
  },
 
  /**
   * 生命周期函数--监听页面加载
   */
  onLoad: function (options) {
    qqmapsdk = new QQMapWX({
      key: '自己申请一个腾讯位置服务的key'
    });
  },
  bindLocationInput:function(e){
    var that = this;
    // 逆向解析
    qqmapsdk.reverseGeocoder({
      location: '', //获取表单传入的位置坐标,不填默认当前位置,示例为string格式
      //get_poi: 1, //是否返回周边POI列表：1.返回；0不返回(默认),非必须参数
      success: function(res) {//成功后的回调
    
        if(res.status==0){

          let locationInfo  = {}
          locationInfo.province = res.result.address_component.province;
          locationInfo.city = res.result.address_component.city;
          locationInfo.district = res.result.address_component.district;
          locationInfo.location_name = locationInfo.province+locationInfo.city+locationInfo.district+res.result.formatted_addresses.recommend;

          console.log(locationInfo.lat_dest+','+locationInfo.lng_dest);

          that.setData({location_info:locationInfo});
          // 计算位置
          qqmapsdk.calculateDistance({
          
            from: '', //若起点有数据则采用起点坐标，若为空默认当前地址
            to: that.data.lat_dest+','+that.data.lng_dest, //终点坐标
            success: function(res) {//成功后的回调
              
              var distance = res.result.elements[0].distance;
              console.log('distance==',distance);
               
            },
            fail: function(error) {
              console.error(error);
            },
            complete: function(res) {
              console.log(res);
            }

          });

          that.setData({report_info:locationInfo});
        }else{

          return app.Tips({title:'请重试！'});
        }
        
        


      },
      fail: function (res) {
        return app.Tips({title:'请重试！'});
    },
     complete: function (res) {
      // console.log(res);
    }

    });
  },
})