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As react native developers, one of the most important things we need to learn is React Native’s lifecycle. This lets us know when and how our code will run. In this blog post, we’ll discuss the different phases of React Native’s lifecycle and what they mean for your development process.
There are three main phases in React Native’s lifecycle: mounting, updating, and unmounting. Let’s take a look at each one in more detail.
Mounting
The first phase is mounting. This is when React Native starts up and loads all the necessary components for your app. During this phase, your code will be executed so that the React Native system can start initializing.
constructor(): This is the first function that will be called when your component is being mounted. This is where you can initialize the state and props for your component.
static getDerivedStateFromProps(): This function is called after the constructor and before the render function. It can be used to update the state of your component based on props changes.
render(): This is the function that actually renders your component to the screen. It should return a React element, which can be a JSX template, a string, or a React component.
componentDidMount(): This function is called after the render function. It can be used to perform any last-minute operations, such as fetching data or setting up event listeners.
Updating
Once all the components are mounted, React Native will move on to the next phase: updating. This is where most of your code will be executed. react-native will call your code when it needs to re-render or update a component. This phase is important for keeping your app up-to-date with the latest data.
static getDerivedStateFromProps(): This function is called whenever props are updated. It can be used to update the state of your component based on props changes.
shouldComponentUpdate(): This function is called before the render function. It can be used to prevent unnecessary re-rendering of your component.
render(): This function is called whenever the component needs to be updated. It should return a React element, which can be a JSX template, a string, or a React component.
getSnapshotBeforeUpdate(): This function is called after the render function and before the updated component is actually committed to the screen. It can be used to perform any last-minute operations, such as fetching data or setting up event listeners.
componentDidUpdate(): This function is called after the updated component is committed to the screen. It can be used to perform any post-update operations, such as cleanup or logging.
Unmounting
The last phase is unmounting. This is when React Native cleans up and destroys all the components in your app. This usually happens when the user closes the app or navigates to another screen. During this phase, react-native will call your code so that you can clean up any resources that your app is using.
componentWillUnmount(): This function is called before the component is unmounted. It can be used to perform any cleanup operations, such as removing event listeners or canceling network requests.
Error Handling
There is one more phase that we didn’t mention: error handling. This phase is executed when there is an error in your code. react-native will call your code so that you can handle the error and prevent it from crashing your app.
static getDerivedStateFromError(): This function is called whenever there is an error in your code. It can be used to update the state of your component so that you can handle the error.
componentDidCatch(): This function is called after the static getDerivedStateFromError() function. It can be used to perform any post-error handling operations, such as logging the error or displaying an error message to the user.
That’s it! That’s the react-native lifecycle. Now that you know how it works, you can start writing your own react-native components.
React Native’s lifecycle is important to understand because it dictates when and how your code will be executed. By understanding the lifecycle, you can optimize your code so that it runs more efficiently. If you have any questions about React Native’s lifecycle, feel free to leave a comment below! Thanks for reading!
