Merge pull request #12749 from Strate/react_virtualized_window_scroller_types

react-virtualized: improve types of WindowScroller

react-virtualized/index.d.ts

@@ -118,6 +118,23 @@ declare module "react-virtualized" {
     type ScrollSyncProps = any;
     export class ScrollSync extends React.Component<ScrollSyncProps, {}> { }
 
-    type WindowScrollerProps = any;
-    export class WindowScroller extends React.Component<WindowScrollerProps, {}> { }
+    export module WindowScroller {
+        export type OnResizeArg = {
+            height: number;
+        }
+        export type OnScrollArg = {
+            scrollTop: number;
+        }
+        export type RenderCallbackArg = {
+            height: number;
+            scrollTop: number;
+            isScrolling: boolean;
+        }
+        export type Props = {
+            onScroll?: (arg: OnScrollArg) => void;
+            onResize?: (arg: OnResizeArg) => void;
+            // TODO `children` should be typed here
+        };
+    }
+    export class WindowScroller extends React.Component<WindowScroller.Props, {}> { }
 }

react-virtualized/react-virtualized-tests.tsx

@@ -291,9 +291,11 @@ function ScrollSyncTest() {
 }
 
 function WindowScrollerTest() {
+    const onScroll = function({scrollTop}: WindowScroller.OnScrollArg) {};
+    const onResize = function({height}: WindowScroller.OnResizeArg) {};
     ReactDOM.render(
-        <WindowScroller>
-            {({ height, isScrolling, scrollTop }) => (
+        <WindowScroller onScroll={onScroll} onResize={onResize}>
+            {({ height, isScrolling, scrollTop }: WindowScroller.RenderCallbackArg) => (
                 <VirtualScroll
                     autoHeight
                     height={height}
@@ -306,4 +308,9 @@ function WindowScrollerTest() {
         </WindowScroller>,
         document.getElementById('example')
     );
+    // test that onScroll & onResize are optional
+    ReactDOM.render(
+        <WindowScroller />,
+        document.getElementById('example')
+    );
 }