Type selection object in getDraftEditorSelection.js

Summary: We were missing a possible case: if there has been no selection, anchorNode and focusNode can be null.

Reviewed By: jack-arms

Differential Revision: D21002172

fbshipit-source-id: d84a5c6eb551d88898148d84e4961515f152f02c

src/component/selection/getDraftEditorSelection.js

@@ -12,6 +12,7 @@
 'use strict';
 
 import type {DOMDerivedSelection} from 'DOMDerivedSelection';
+import type {SelectionObject} from 'DraftDOMTypes';
 import type EditorState from 'EditorState';
 
 const getDraftEditorSelectionWithNodes = require('getDraftEditorSelectionWithNodes');
@@ -24,10 +25,23 @@ function getDraftEditorSelection(
   editorState: EditorState,
   root: HTMLElement,
 ): DOMDerivedSelection {
-  const selection = root.ownerDocument.defaultView.getSelection();
+  const selection: SelectionObject = root.ownerDocument.defaultView.getSelection();
+  const {
+    anchorNode,
+    anchorOffset,
+    focusNode,
+    focusOffset,
+    rangeCount,
+  } = selection;
 
-  // No active selection.
-  if (selection.rangeCount === 0) {
+  if (
+    // No active selection.
+    rangeCount === 0 ||
+    // No selection, ever. As in, the user hasn't selected anything since
+    // opening the document.
+    anchorNode == null ||
+    focusNode == null
+  ) {
     return {
       selectionState: editorState.getSelection().set('hasFocus', false),
       needsRecovery: false,
@@ -37,10 +51,10 @@ function getDraftEditorSelection(
   return getDraftEditorSelectionWithNodes(
     editorState,
     root,
-    selection.anchorNode,
-    selection.anchorOffset,
-    selection.focusNode,
-    selection.focusOffset,
+    anchorNode,
+    anchorOffset,
+    focusNode,
+    focusOffset,
   );
 }