hook made for listening to resize events ie use-on-resize.js, with a debounced callback as to make performance even better.

ui/component/common/tabs.jsx

@@ -8,6 +8,7 @@ import {
   TabPanel as ReachTabPanel,
 } from '@reach/tabs';
 import classnames from 'classnames';
+import { useOnResize } from '../../effects/use-on-resize';
 
 // Tabs are a compound component
 // The components are used individually, but they will still interact and share state
@@ -45,22 +46,14 @@ function Tabs(props: TabsProps) {
   const [tabsRect, setTabsRect] = React.useState();
 
   // Create a ref of the parent element so we can measure the relative "left" for the bar for the child Tab's
-  // Don't observe as its going to re-render when the window size changes anyway
   const tabsRef = useRef<Element | void | null>();
 
-  function changeWindowSize() {
+  // Recalculate "Rect" on window resize
+  useOnResize(() => {
     if (tabsRef.current) {
-      setTabsRect(tabsRef.current.getBoundingClientRect() || undefined);
+      setTabsRect(tabsRef.current.getBoundingClientRect());
     }
-  }
+  });
-
-  React.useEffect(() => {
-    window.addEventListener('resize', changeWindowSize);
-
-    return () => {
-      window.removeEventListener('resize', changeWindowSize);
-    };
-  }, []);
 
   const tabLabels = props.children[0];
   const tabContent = props.children[1];
@@ -107,22 +100,14 @@ function Tab(props: TabProps) {
   const { isSelected } = props;
   const [rect, setRect] = React.useState();
 
-  function changeWindowSize() {
+  // Recalculate "Rect" on window resize
+  useOnResize(() => {
     if (ref.current) {
-      setRect(ref.current.getBoundingClientRect() || undefined);
+      setRect(ref.current.getBoundingClientRect());
     }
-  }
+  });
-
-  React.useEffect(() => {
-    window.addEventListener('resize', changeWindowSize);
-
-    return () => {
-      window.removeEventListener('resize', changeWindowSize);
-    };
-  }, []);
 
   // Each tab measures itself
-  // Don't observe as its going to re-render when the window size changes anyway
   const ref = useRef<Element | void | null>();
 
   // and calls up to the parent when it becomes selected

ui/effects/use-on-resize.js

@@ -1,15 +1,14 @@
 import { useEffect } from 'react';
+import debounce from 'util/debounce';
 
 export function useOnResize(cb) {
   useEffect(() => {
-    function handleResize() {
+    const handleResize = debounce(cb, 100);
-      cb();
-    }
 
     window.addEventListener('resize', handleResize);
 
     handleResize();
 
     return () => window.removeEventListener('resize', handleResize);
-  }, [cb]);
+  }, []);
 }