$.ajax({
      url: '/ao16/get-heat-map',//url of the function, this should be set in urls.py
      dataType: 'json',
      jsonpCallback: 'getJson',
      beforeSend: function() {
        $('#loader').show();
      },
      success: function(response) {
        $('#loader').hide();
        if (checked && heat == null){
          heat = L.heatLayer(response.proposed_roads, {
              radius: 25,
              blur: 25,
              gradient: {
                0.47: 'blue',
                0.67: 'lime',
                1.0: 'red'
              }
          }).addTo(map);
        }else if (checked){
          map.addLayer(heat)
        }
      }
    })