diff --git a/src/filemanager.html b/src/filemanager.html
index d76f9ee87..4b7ca087b 100644
--- a/src/filemanager.html
+++ b/src/filemanager.html
@@ -196,6 +196,25 @@
     </div>
   </div>
 
+  <!-- Modal editor close -->
+  <div class="modal fade" id="textEditorCloseModal" tabindex="-1" role="dialog">
+    <div class="modal-dialog">
+      <div class="modal-content">
+        <div class="modal-header">
+          <h4 class="modal-title">File has unsaved changes</h4>
+        </div>
+        <div class="modal-body">
+          <p class="text-bold text-danger">Your changes will be lost if you don't save them</p>
+        </div>
+        <div class="modal-footer">
+          <button type="button" class="btn btn-default" ng-click="textEditor.close()">Don't Save</button>
+          <button type="button" class="btn btn-default" data-dismiss="modal">Cancel</button>
+          <button type="button" class="btn btn-success" ng-click="textEditor.saveAndClose()"><i class="fa fa-circle-notch fa-spin" ng-show="textEditor.busy"></i> Save</button>
+        </div>
+      </div>
+    </div>
+  </div>
+
   <div class="main-container animateMe ng-hide layout-root" ng-show="initialized">
     <div ng-show="view === 'fileTree'" class="layout-content container">
       <div class="row" ng-hide="app">
@@ -262,9 +281,9 @@
     <div ng-show="view === 'textEditor'" class="text-editor">
       <div>
         <div class="toolbar">
-          <button type="button" class="btn btn-success" ng-click="textEditor.save()" ng-disabled="textEditor.busy"><i class="fa fa-circle-notch fa-spin" ng-show="textEditor.busy"></i> Save</button>
           <div><span>{{ textEditor.entry.fileName }}</span></div>
-          <button type="button" class="btn btn-primary" ng-click="textEditor.close()">Close</button>
+          <button type="button" class="btn btn-success" ng-click="textEditor.save()" ng-disabled="textEditor.busy"><i class="fa fa-circle-notch fa-spin" ng-show="textEditor.busy"></i> Save</button>
+          <button type="button" class="btn btn-primary" ng-click="textEditor.maybeClose()">Close</button>
         </div>
       </div>
       <div id="textEditorContainer" style="flex-grow: 2; border: 0px solid black"></div>
diff --git a/src/js/filemanager.js b/src/js/filemanager.js
index 963010734..bc25f7c3b 100644
--- a/src/js/filemanager.js
+++ b/src/js/filemanager.js
@@ -436,10 +436,12 @@ app.controller('FileManagerController', ['$scope', '$timeout', 'Client', functio
         busy: false,
         entry: null,
         editor: null,
+        unsaved: false,
 
         show: function (entry) {
             $scope.textEditor.entry = entry;
             $scope.textEditor.busy = false;
+            $scope.textEditor.unsaved = false;
 
             // clear model if any
             if ($scope.textEditor.editor && $scope.textEditor.editor.getModel()) $scope.textEditor.editor.setModel(null);
@@ -460,14 +462,16 @@ app.controller('FileManagerController', ['$scope', '$timeout', 'Client', functio
                             language: language,
                             theme: 'vs-dark'
                         });
+                        $scope.textEditor.editor.getModel().onDidChangeContent(function () { $scope.textEditor.unsaved = true; });
                     }, 200);
                 } else {
                     $scope.textEditor.editor.setModel(monaco.editor.createModel(result, 'javascript'));
+                    $scope.textEditor.editor.getModel().onDidChangeContent(function () { $scope.textEditor.unsaved = true; }); // have to re-attach whenever model changes
                 }
             });
         },
 
-        save: function () {
+        save: function (callback) {
             $scope.textEditor.busy = true;
 
             var newContent = $scope.textEditor.editor.getValue();
@@ -475,14 +479,31 @@ app.controller('FileManagerController', ['$scope', '$timeout', 'Client', functio
             var file = new File([newContent], 'file');
 
             Client.filesUpload($scope.appId, filePath, file, function () {}, function (error) {
-                $scope.textEditor.busy = false;
                 if (error) return Client.error(error);
+
+                $timeout(function () {
+                    $scope.textEditor.unsaved = false;
+                    $scope.textEditor.busy = false;
+                    if (callback) return callback();
+                }, 1000);
             });
         },
 
         close: function () {
             $scope.view = 'fileTree';
-        }
+            $('#textEditorCloseModal').modal('hide');
+        },
+
+        saveAndClose: function () {
+            $scope.textEditor.save(function () {
+                $scope.textEditor.close();
+            });
+        },
+
+        maybeClose: function () {
+            if (!$scope.textEditor.unsaved) return $scope.textEditor.close();
+            $('#textEditorCloseModal').modal('show');
+        },
     };
 
     $scope.chownEntry = {