Add state saving to Container

src/Components/CreateEditorApp/CreateEditorApp.tsx

@@ -17,7 +17,7 @@ interface CreateEditorAppState {
 }
 
 export class CreateEditorApp extends React.Component<{}, CreateEditorAppState> {
-  localStorageKey: 'appData';
+  localStorageKey: string = 'appData';
 
   constructor(props: {}) {
     super(props);

src/Components/DragContainer/DragContainer.tsx

@@ -22,6 +22,8 @@ interface DragContainerState {
 }
 
 export class DragContainer extends React.Component<DragContainerProps, DragContainerState> {
+    localStorageKey: string = 'containerData';
+
     constructor(props: DragContainerProps) {
         super(props);
 
@@ -42,6 +44,30 @@ export class DragContainer extends React.Component<DragContainerProps, DragConta
         this.handleDragStop = this.handleDragStop.bind(this);
     }
 
+    componentDidMount() {
+        this.loadFromLocalStorage();
+    }
+
+    componentDidUpdate() {
+        this.saveToLocalStorage();
+    }
+
+    saveToLocalStorage() {
+        const pastOffsetJSON = JSON.stringify(this.state.pastCumulativeOffsetMap);
+        localStorage.setItem(this.localStorageKey, pastOffsetJSON);
+    }
+
+    loadFromLocalStorage() {
+        const pastOffsetJSON = localStorage.getItem(this.localStorageKey);
+
+        if (pastOffsetJSON) {
+            const pastOffsetObject = JSON.parse(pastOffsetJSON);
+            this.setState({
+                pastCumulativeOffsetMap: pastOffsetObject
+            });
+        }
+    }
+
     handleDragStartOnDraggableNode(draggableId: string, ev: React.MouseEvent<HTMLDivElement>): void {
         this.setState({
             ongoing: {