Add useComponentWillUnmount

snippets/useComponentWillUnmount.md

@@ -0,0 +1,26 @@
+---
+title: useComponentWillUnmount
+tags: hooks,effect,beginner
+---
+
+A hook that executes a callback immediately before a component is unmounted and destroyed.
+
+- Use `React.useEffect()` with an empty array as the second argument and return the provided callback to be executed only once before cleanup.
+
+```jsx
+const useComponentWillUnmount = onUnmountHandler => {
+  React.useEffect(() => () => {
+    onUnmountHandler()
+  }, []);
+}
+```
+
+```jsx
+const Unmounter = () => {
+  useComponentWillUnmount(() => console.log('Component will unmount'));
+
+  return <div>Check the console!</div>;
+}
+
+ReactDOM.render(<Unmounter />, document.getElementById('root'));
+```