refactor(useRect,useScroll): make observation simpler

Author: tannerlinsley

src/useRect.js

@@ -23,16 +23,16 @@ export default function useRect(nodeRef) {
   }, [element])
 
   React.useEffect(() => {
-    let observer
-
-    if (element) {
-      observer = observeRect(element, setRect)
+    if (!element) {
+      return
     }
 
-    observer && observer.observe()
+    const observer = observeRect(element, setRect)
+
+    observer.observe()
 
     return () => {
-      observer && observer.unobserve()
+      observer.unobserve()
     }
   }, [element])
 

src/useScroll.js

@@ -23,22 +23,24 @@ export default function useScroll(nodeRef, onChange) {
   }, [element])
 
   React.useEffect(() => {
+    if (!element) {
+      return
+    }
+
     const handler = e => {
       onChangeRef.current({
         scrollLeft: e.target.scrollLeft,
         scrollTop: e.target.scrollTop,
       })
     }
 
-    if (element) {
-      element.addEventListener('scroll', handler, {
-        capture: false,
-        passive: true,
-      })
+    element.addEventListener('scroll', handler, {
+      capture: false,
+      passive: true,
+    })
 
-      return () => {
-        element.removeEventListener('scroll', handler)
-      }
+    return () => {
+      element.removeEventListener('scroll', handler)
     }
   }, [element])
 }