Refactor collapse handling into Elevation

as it's the only element it is intended for, sidebar uses separate handling.

js/index.js

@@ -420,38 +420,11 @@
             urlHash
         );
 
+        // listener and initCollapse here and not in onAdd, as addBelow calls addTo (-> onAdd) on resize
         $(window).resize(function() {
             elevation.addBelow(map);
         });
-
+        elevation.initCollapse(map);
-        $('#elevation-chart').on('show.bs.collapse', function() {
-            $('#elevation-btn').addClass('active');
-        });
-        $('#elevation-chart').on('hidden.bs.collapse', function() {
-            $('#elevation-btn').removeClass('active');
-            // we must fetch tiles that are located behind elevation-chart
-            map._onResize();
-        });
-
-        var onHide = function() {
-            if (this.id && BR.Util.localStorageAvailable()) {
-                localStorage.removeItem(this.id);
-            }
-        };
-        var onShow = function() {
-            if (this.id && BR.Util.localStorageAvailable()) {
-                localStorage[this.id] = 'true';
-            }
-        };
-        // on page load, we want to restore collapsible elements from previous usage
-        $('.collapse')
-            .on('hidden.bs.collapse', onHide)
-            .on('shown.bs.collapse', onShow)
-            .each(function() {
-                if (this.id && BR.Util.localStorageAvailable() && localStorage[this.id] === 'true') {
-                    $(this).collapse('show');
-                }
-            });
     }
 
     i18next.on('languageChanged', function(detectedLanguage) {

js/plugin/Elevation.js

@@ -55,6 +55,34 @@ BR.Elevation = L.Control.Elevation.extend({
         setParent(this.getContainer(), document.getElementById('elevation-chart'));
     },
 
+    initCollapse: function(map) {
+        var onHide = function() {
+            $('#elevation-btn').removeClass('active');
+            // we must fetch tiles that are located behind elevation-chart
+            map._onResize();
+
+            if (this.id && BR.Util.localStorageAvailable()) {
+                localStorage.removeItem(this.id);
+            }
+        };
+        var onShow = function() {
+            $('#elevation-btn').addClass('active');
+
+            if (this.id && BR.Util.localStorageAvailable()) {
+                localStorage[this.id] = 'true';
+            }
+        };
+        // on page load, we want to restore collapse state from previous usage
+        $('#elevation-chart')
+            .on('hidden.bs.collapse', onHide)
+            .on('shown.bs.collapse', onShow)
+            .each(function() {
+                if (this.id && BR.Util.localStorageAvailable() && localStorage[this.id] === 'true') {
+                    $(this).collapse('show');
+                }
+            });
+    },
+
     update: function(track, layer) {
         this.clear();