fix(apis_entities): fix, update map JS

Fix references to longitude, latitude values,
incorrect check for existing map; update variable
names, keywords following JavaScript best practices,
reorder statements for readabilty.

Closes: #639

apis_core/apis_entities/templates/apis_core/apis_entities/abstractentity_form.html

@@ -172,25 +172,31 @@
 };
 activate_editing();
 
-function showmap(element) {
+function showMap(element) {
   $('.popover').remove();
-  var rect = element.getBoundingClientRect();
-
-  mapdiv = document.createElement("div");
-  mapdiv.classList.add("popover");
-  mapdiv.setAttribute("id", "popovermap");
-  ptop = rect.top + window.scrollY - 250;
-  pleft = rect.left + window.scrollX - 550;
-  $(mapdiv).offset({top: ptop, left: pleft});
-  document.body.appendChild(mapdiv);
-
-  if (typeof map != "undefined") { map.off(); map.remove(); }
-  map = L.map('popovermap', { center: [element.dataset.lat, element.dataset.lng], zoom: 5 });
-  L.tileLayer('https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', { attribution: '&copy; <a href="https://www.openstreetmap.org/copyright">OpenStreetMap</a> contributors' }).addTo(map);
-  L.marker([element.dataset.lat, element.dataset.lng]).addTo(map);
-};
+  let map;
+
+  let rect = element.getBoundingClientRect();
+  let pTop = rect.top + window.scrollY - 250;
+  let pLeft = rect.left + window.scrollX - 550;
+
+  let mapDiv = document.createElement("div");
+  mapDiv.classList.add("popover");
+  mapDiv.setAttribute("id", "popovermap");
+
+  $(mapDiv).offset({top: pTop, left: pLeft});
+  document.body.appendChild(mapDiv);
+
+  if (typeof map !== "undefined") { map.off(); map.remove(); }
+
+  map = L.map('popovermap', { center: [parseInt(element.dataset.latitude), parseInt(element.dataset.longitude)], zoom: 5 });
+  L.tileLayer('https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', {
+    attribution: '&copy; <a href="https://www.openstreetmap.org/copyright">OpenStreetMap</a> contributors'
+  }).addTo(map);
+  L.marker([parseInt(element.dataset.latitude), parseInt(element.dataset.longitude)]).addTo(map);
+}
 
-function delmap(element) {
+function delMap(element) {
   $('.popover').remove();
 }
   </script>