add unbeforeunload in editor if currently editing something

src/c3nav/editor/static/editor/js/editor.js

@@ -24,6 +24,7 @@ editor = {
         editor.map.on('click', function () {
             editor.map.doubleClickZoom.enable();
         });
+        window.onbeforeunload = editor._onbeforeunload;
 
         L.control.scale({imperial: false}).addTo(editor.map);
 
@@ -46,6 +47,11 @@ editor = {
         editor.map.setMaxBounds(bounds);
         editor.map.fitBounds(bounds, {padding: [30, 50]});
     },
+    _onbeforeunload: function(e) {
+        if ($('#sidebar').find('[data-onbeforeunload]').length) {
+            e.returnValue = true;
+        }
+    },
 
     // sources
     sources: {},

src/c3nav/editor/templates/editor/edit.html

@@ -11,7 +11,7 @@
 {% else %}
     <h3>{% blocktrans %}Edit {{ model_title }}{% endblocktrans %}</h3>
 {% endif %}
-<form action="{{ path }}" method="post">
+<form action="{{ path }}" method="post" data-onbeforeunload>
     {% csrf_token %}
     {% bootstrap_form form %}
     {% buttons %}