What Are Lifecycle Methods In React?

React Lifecycle Methods


React lifecycle methods are integral to building dynamic and efficient React applications. They offer developers a structured way to manage the various stages of a component’s existence, from its initial rendering to its removal from the DOM. These methods enable precise control over how components behave and interact with the DOM, handle state and props updates, and perform necessary cleanup tasks. By leveraging lifecycle methods, developers can optimize performance, ensure proper resource management, and handle errors gracefully, resulting in more robust and maintainable applications. Understanding React lifecycle methods from the Best React JS Course is essential for any developer aiming to create high-quality React components.

What Are React Lifecycle Methods?

React lifecycle methods are a series of events that happen from the birth, growth, to the death of a React component. They provide hooks that allow developers to run code at particular moments in a component’s life.

Lifecycle methods can be divided into three phases: mounting, updating, and unmounting.


When a component is being inserted into the DOM, the following methods are called in order:

  • constructor(): This method is called before the component is mounted. It is used to initialize state and bind methods.
  • static getDerivedStateFromProps(props, state): This method is called right before rendering, both during the initial mount and subsequent updates. It returns an object to update the state based on the props or null if no state updates are needed. The React JS Certification course trains professionals in all these methods.
  • render(): This method is required and returns the JSX that makes up the component’s structure. It should be pure and not contain side effects.
  • componentDidMount(): This method is called immediately after the component is mounted. It’s a good place to make network requests, set up subscriptions, or interact with the DOM.


When a component is being re-rendered due to changes in props or state, the following methods are called in order:

  • static getDerivedStateFromProps(props, state): Called again to update the state based on props.
  • shouldComponentUpdate(nextProps, nextState): This method is called before rendering when new props or state are received. It returns a boolean to determine if the component should update.
  • render(): Called again to re-render the component.
  • getSnapshotBeforeUpdate(prevProps, prevState): Called right before the DOM is updated. It can capture information (like scroll position) before the changes are made. It returns a value that will be passed to componentDidUpdate().
  • componentDidUpdate(prevProps, prevState, snapshot): Called immediately after the DOM is updated. It’s a good place to make network requests in response to changes or to perform DOM operations.


When a component is being removed from the DOM, the following method is called:

  • componentWillUnmount(): This method is called immediately before a component is destroyed. It’s used for cleanup, such as invalidating timers, canceling network requests, or cleaning up subscriptions.

Error Handling

React also provides methods for handling errors in the lifecycle:

  • static getDerivedStateFromError(error): This method is called when an error is thrown in a descendant component. It updates the state to display an error message.
  • componentDidCatch(error, info): This method is called when an error is thrown in a descendant component. It can log error information or perform other actions.

Understanding these lifecycle methods is crucial for effectively managing the behavior of React components and ensuring optimal performance and user experience.

Why Do We Need React Lifecycle Methods?

React lifecycle methods are essential for managing the various stages of a component’s existence in a React application. They provide hooks that allow developers to execute code at specific points during the component’s life cycle, ensuring that the component behaves predictably and efficiently. One can join the Best React JS Courseto learn more about React lifecycle methods.

Here are the key reasons why we need React lifecycle methods:

Initialization and Setup

  • State Initialization: The constructor() method is used to initialize the component’s state. This is crucial for setting up the initial conditions for a component.
  • Event Binding: Within the constructor(), developers can bind event handlers to ensure the correct context is maintained when these handlers are invoked.

DOM Interaction and Side Effects

  • DOM Manipulation: Methods like componentDidMount() are used to interact with the DOM after the component has been rendered. This is ideal for initializing plugins, setting up event listeners, or performing actions that require the DOM to be in place.
  • Data Fetching: componentDidMount() is also commonly used to fetch data from APIs. This ensures that data fetching happens after the component is part of the DOM, preventing race conditions and ensuring a smooth user experience.

Performance Optimization

  • Conditional Rendering: shouldComponentUpdate() allows developers to control when a component should re-render. By returning false when updates are unnecessary, performance can be significantly improved.
  • Snapshot Handling: getSnapshotBeforeUpdate() captures the state of the DOM before changes are made, allowing developers to manage side effects like scroll positions more effectively.


  • Resource Management: componentWillUnmount() is crucial for cleanup operations. It ensures that any subscriptions, timers, or network requests initiated by the component are properly disposed of, preventing memory leaks and unwanted behaviors.

Error Handling

  • Graceful Degradation: getDerivedStateFromError() and componentDidCatch() provide mechanisms to handle errors gracefully. These methods ensure that errors in child components don’t crash the entire application, improving robustness and user experience.

State and Props Synchronization

  • State Updates from Props: getDerivedStateFromProps() allows components to update their internal state based on changes in props, ensuring that the component reflects the latest data.


React lifecycle methods are essential for managing a component’s existence, from initialization to destruction. They enable efficient DOM interactions, performance optimizations, resource management, and error handling, ensuring robust and predictable component behavior. Consider joining the React JS Certification course for the best guidance and training. Understanding and utilizing these methods is crucial for developing effective and maintainable React applications.

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