content/snippets/react/s/use-component-did-update.md
---
title: React useComponentDidUpdate hook
type: snippet
language: react
tags: [hooks,effect]
cover: flower-portrait-10
dateModified: 2021-11-09
---
Executes a callback immediately after a component is updated.
- Use the `useRef()` hook to create a variable, `mounted`, that tracks if the component has been mounted.
- Use the `useEffect()` hook to set the value of `mounted` to `true` the first time the hook is executed.
- Run the provided `callback` on subsequent hook executions.
- Providing a dependency array for the second argument, `condition`, will only execute the hook if any of the dependencies change.
- Behaves like the `componentDidUpdate()` lifecycle method of class components.
```jsx
const useComponentDidUpdate = (callback, condition) => {
const mounted = React.useRef(false);
React.useEffect(() => {
if (mounted.current) callback();
else mounted.current = true;
}, condition);
};
const App = () => {
const [value, setValue] = React.useState(0);
const [otherValue, setOtherValue] = React.useState(1);
useComponentDidUpdate(() => {
console.log(`Current value is ${value}.`);
}, [value]);
return (
<>
<p>
Value: {value}, other value: {otherValue}
</p>
<button onClick={() => setValue(value + 1)}>Increment value</button>
<button onClick={() => setOtherValue(otherValue + 1)}>
Increment other value
</button>
</>
);
};
ReactDOM.createRoot(document.getElementById('root')).render(
<App />
);
```