assign null value in merge util. fire changeend event on start.

lib/layer/format/vector.mjs

@@ -116,15 +116,24 @@ export default layer => {
 
   layer.setSource(layer.features)
 
-  // Add event listener to reload layer for viewport on changeEnd.
-  layer.params.viewport && layer.mapview.Map.getTargetElement().addEventListener('changeEnd', ()=>{
+  // Add event listener to reload layer for viewport or layer.tables on changeEnd.
+  if (layer.tables || layer.params.viewport) {
 
-    if (!layer.display) return;
+    layer.mapview.Map.getTargetElement().addEventListener('changeEnd', () => {
 
-    clearTimeout(layer.timeout)
+      // Layer is outside of tables zoom range.
+      if (!layer.tableCurrent()) {
+        layer.L.setSource(null)
+        return;
+      }
 
-    layer.timeout = setTimeout(layer.reload, 100)
-  })
+      if (!layer.display) return;
+
+      clearTimeout(layer.timeout)
+
+      layer.timeout = setTimeout(layer.reload, 100)
+    })
+  }
 
   // Change method for the cluster feature properties and layer stats.
   layer.L.on('change', e => {

lib/mapview/_mapview.mjs

@@ -244,7 +244,9 @@ export default (mapview) => {
   })
 
   // changeEnd
-  mapview.Map.getTargetElement().addEventListener('changeEnd', () => {
+  mapview.Map.getTargetElement().addEventListener('changeEnd', changeEnd)
+
+  function changeEnd() {
 
     // Update URL params if enabled on mapview
     if (!mapview.hooks) return;
@@ -261,7 +263,7 @@ export default (mapview) => {
       lng: Math.round((center[0] + Number.EPSILON) * 100000) / 100000,
       z: Math.round((mapview.Map.getView().getZoom() + Number.EPSILON) * 100) / 100
     })
-  })
+  }
 
   // Timer to debounce changeEnd event.
   let changeEndTimer
@@ -275,5 +277,9 @@ export default (mapview) => {
     }, 500)
   })
 
+  changeEndTimer = setTimeout(() => {
+    mapview.Map.getTargetElement().dispatchEvent(new CustomEvent('changeEnd'))
+  }, 500)
+
   return mapview
 }

lib/ui/layers/view.mjs

@@ -114,14 +114,18 @@ export default (layer) => {
 
   // The layer view drawer should be disabled if layer.tables are not available for the current zoom level.
   layer.mapview.Map.getTargetElement().addEventListener('changeEnd', ()=>{
+
     if (!layer.tables) return;
+
     if (layer.tableCurrent() === null) {
 
-      // Disable layer view out of zoom range
+      // Collapse drawer and disable layer.view.
       layer.view.querySelector('[data-id=layer-drawer]').classList.remove('expanded')
       layer.view.classList.add('disabled')
+
     } else {
 
+      // Enable the layer.view.
       layer.view.classList.remove('disabled')
     }
 

lib/utils/merge.mjs

@@ -5,25 +5,38 @@
     return target;
   }
 
+  // Shift first source out of sources array.
   const source = sources.shift();
 
+  // target & source are both objects.
   if (isObject(target) && isObject(source)) {
 
+    const proto = Object.getPrototypeOf(target)
+
     // Iterate over object keys in source.
     for (const key in source) {
 
-      if (isObject(source[key])) {
+      // Key must not be in target object prototype.
+      if (proto[key]) {
+        console.warn(`Prototype polution detected for key: ${key}`)
+        continue;
+      }
+
+      if (source[key] === null) {
+        target[key] = null;
+
+      } else if (isObject(source[key])) {
 
-        // Assign empty object on key.
-        if (!target[key]) Object.assign(target, { [key]: {} });
+        // Target key must be an object.
+        target[key] ??= {}
 
         // Call recursive merge for target key object.
         mergeDeep(target[key], source[key]);
 
       } else {
 
-        // Assign key if not an object itself.
-        Object.assign(target, { [key]: source[key] });
+        // source[key] is neither null nor object.
+        target[key] = source[key]
       }
     }
   }
@@ -33,11 +46,13 @@
 
 function isObject(item) {
 
+  // item is an HTMLElement 
   if (item instanceof HTMLElement) {
     console.warn(item)
     return false;
   }
 
+  // item is an array.
   if (Array.isArray(item)) return false;
 
   if (typeof item === 'object') return true;