Add note about why casting event.type to a topLevelType is safe

facebook · Sep 11, 2018 · 4e1f1a6 · 4e1f1a6
1 parent 7d2b2f1
commit 4e1f1a6
Showing 1 changed file with 1 addition and 0 deletions.
diff --git a/packages/react-dom/src/events/ReactDOMEventListener.js b/packages/react-dom/src/events/ReactDOMEventListener.js
@@ -57,6 +57,7 @@ function getTopLevelCallbackBookKeeping(
   targetInst: Fiber | null,
   ancestors: Array<Fiber>,
 } {
+  // This is safe because DOMTopLevelTypes are always native event type strings
   const topLevelType = unsafeCastStringToDOMTopLevelType(nativeEvent.type);
 
   if (callbackBookkeepingPool.length) {