script.js

$( document ).ready(function() {
    get_distances();
});

function getDistanceFromLatLonInKm(lat1,lon1,lat2,lon2) {
  var R = 6371; // Radius of the earth in km
  var dLat = deg2rad(lat2-lat1);  // deg2rad below
  var dLon = deg2rad(lon2-lon1);
  var a =
    Math.sin(dLat/2) * Math.sin(dLat/2) +
    Math.cos(deg2rad(lat1)) * Math.cos(deg2rad(lat2)) *
    Math.sin(dLon/2) * Math.sin(dLon/2)
    ;
  var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
  var d = R * c; // Distance in km
  return d;
}

function deg2rad(deg) {
  return deg * (Math.PI/180)
}

function get_by_cat(obj, ID){
  $('.orderlist-div').toggleClass('d-none',true);
  $('.cat-'+ID).toggleClass('d-none',false);
  $('.categories li').toggleClass('active', false );
  $(obj).toggleClass('active',true);
}

function get_distances(){
  var url_string = window.location.href;
  var url = new URL(url_string);
  var lat = url.searchParams.get('lat');
  var long = url.searchParams.get('long');
  if( lat == null || long == null ){
    lat=-100;
  }
  var calc_distance=false;
  if( lat >= -90 && lat <= 90 && long >=-180 && long <= 180 ){
    calc_distance=true;
  }

  $.each( $('.distance'), function(i,v){
    var geo=$( $(v).context.previousElementSibling ).text();
    var llat=geo.split(/,/g)[0];
    var llong=geo.split(/,/g)[1];
    var lcountry=geo.split(/,/g)[2];
    $(v).html('<span class="feather-icon icon-map-pin"></span> ' + lcountry + ' ' + (( calc_distance ) ? '( ' + Math.round( getDistanceFromLatLonInKm (lat, long, llat, llong ) )+'km ) ' : '' ) );
  } );
}