What are ReactJS Component Lifecycle Methods?

ReactJS, a popular Javascript library for developing user interfaces, offers a rich set of lifecycle methods that allow developers to manage the behaviour of components throughout their lifecycle. These methods enable control over initialization, rendering, updates, and destruction of components, making it possible to integrate logic at various stages of a component’s existence. This blog will explore “What are ReactJS Component Lifecycle Methods?”. React JS Training in Chennai provide training on React’s core concepts, component-based architecture, state management, hooks, and more. Discover how React simplifies UI development, enhances code reusability, and enables the creation of high-performance web applications.

Component Lifecycle Phases

The three primary stages of a React component’s lifecycle are mounting, updating, and unmounting. At particular times during the lifecycle of a component, React will automatically invoke a set of methods from each phase.

Mounting Phase

1. constructor(): When a component is created, the constructor is the first method to be called. It is employed to bind event handlers and initialize the state. This call only occurs once during the component’s lifecycle; thus, do not execute any side effects.
2. static getDerivedStateFromProps(): This static method is called whenever the props of a component change. It allows the component to update its state based on the incoming props. However, it’s recommended to use other lifecycle methods for managing state updates.
3. render(): The component’s UI representation is created via the render method. Since it is a pure function, it shouldn’t directly interact with the DOM or affect the state.
4. componentDidMount(): This function is invoked when a component is correctly rendered in the DOM. It is frequently used for side effects like data retrieval, DOM manipulation, or subscription setup.

Updating phase

1. static getDerivedStateFromProps(): As mentioned earlier, this method is called during the updating phase, allowing state updates based on changes in props.
2. shouldComponentUpdate(): Developers can choose whether a component should re-render after receiving new props or state using this method. It returns true by default, but you can optimise rendering by having it return false in certain circumstances. Join React JS Online Course and elevate your ReactJS skills by understanding the pivotal shouldComponentUpdate() lifecycle method. Explore how this method allows you to fine-tune component rendering, optimizing performance by selectively updating components.
3. render(): The render method is invoked again to update the component’s UI representation based on new props or states.
4. getSnapshotBeforeUpdate(): This method is called just before component changes are reflected in the DOM. It can capture information about the DOM before an update, which can then be used in ‘componentDidUpdate’.
5. componentDidUpdate(): This function is invoked after the component has been updated and re-rendered. It helps with after-update side effects like DOM interaction or extra data requests.

Unmounting Phase

1. componentWillUnmount(): This function is invoked just before a component is deleted from the DOM. It’s the last chance to finish cleanup operations, such as terminating subscriptions or freeing up resources.

Error Handling Phase

1. static getDerivedStateFromError(): This technique, introduced in React 16, enables a component to detect and address rendering problems in its other components. In the event of an error, it returns a fallback UI representation.
2. componentDidCatch(): This method logs and handles errors caught by the ‘getDerivedStateFromError’ method. It’s commonly used to display an error message and gracefully handle application crashes.

Legacy Lifecycle Methods

It’s important to note that while the lifecycle methods mentioned above provide robust control over component behaviour, some are considered legacy and are being phased out in favour of newer alternatives.

React’s component lifecycle methods offer a structured way to manage the behaviour of components as they are created, updated, and destroyed. As React continues to evolve, keeping up with the recommended practices and new approaches to lifecycle management is essential for maintaining code quality and performance. To learn more about ReactJS, join React JS Course in Chennai and enhance your skills to become an expert in ReactJS.