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react/snippets/use-component-will-unmount.md

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+---
+title: React useComponentWillUnmount hook
+type: snippet
+tags: [hooks,effect]
+author: chalarangelo
+cover: rocky-beach-3
+dateModified: 2021-10-13T19:29:39+02:00
+---
+
+Executes a callback immediately before a component is unmounted and destroyed.
+
+- Use the `useEffect()` hook with an empty array as the second argument. Return the provided callback to be executed only once before cleanup.
+- Behaves like the `componentWillUnmount()` lifecycle method of class components.
+
+```jsx
+const useComponentWillUnmount = onUnmountHandler => {
+  React.useEffect(
+    () => () => {
+      onUnmountHandler();
+    },
+    []
+  );
+};
+```
+
+```jsx
+const Unmounter = () => {
+  useComponentWillUnmount(() => console.log('Component will unmount'));
+
+  return <div>Check the console!</div>;
+};
+
+ReactDOM.createRoot(document.getElementById('root')).render(
+  <Unmounter />
+);
+```