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Lifecycle Methods in Class Components in React

Introduction to React
What is React? Advantages of React JSX syntax Setting up the development environment
Components and Props
Components in React Functional Components Class Components Props PropTypes and defaultProps Component composition
State and Lifecycle Methods
State in React setState method Lifecycle Methods in Class Components Conditional Rendering based on the state
Handling Events
Event handling in React Binding Event Handlers Passing Arguments to Event Handlers Conditional Event Handling
Forms and User Input
Forms in React Controlled Components Uncontrolled Components Form Validation
Lists and Keys
Rendering Lists in React Keys Extracting Components with Keys
Components Lifecycle
Understanding Components Lifecycle Mounting, Updating and Unmounting Lifecycle Methods
Working with APIs
Making HTTP Requests with Axios Handling Responses with Promises Asyncawait syntax for making API calls
React Router
What is React Router? Installation Configuring Routes Navigating between pages using Link and NavLink components
Redux State Management
What is Redux Three principles of Redux Redux Store, Actions, and Reducers ReactRedux integration
Styling React Applications
Styling in React Inline styles CSS Modules Styled Components
Testing React Applications
Testing Fundamentals Testing React Components Integration Testing Using Jest and React Testing Library
Deployment and Optimization
Deployment options for React applications Performance Optimization Code Splitting React Lazy and Suspense
Next Steps
Advanced Topics Resources for continued learning Conclusion

Lifecycle Methods in Class Components

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#description

In React, components have an inherent lifecycle that defines how and when they are rendered, updated and re-rendered. React has several lifecycle methods that are called at specific stages of this lifecycle that we can use to execute code and perform tasks at specific points.

Lifecycle methods can be used in both Functional Components and Class Components in React, but in this case, we will be discussing the Lifecycle Methods in Class Components.

There are three phases of the lifecycle of a Class Component:
  1. Mounting Phase: This is the time when the component is being created and inserted into the DOM.

During this phase, three lifecycle methods are called:
  • constructor() method: This is called when the component is being constructed and is used to set initial state values and bind event handlers. The super() method must be called in the constructor to initialize parent properties.
  • render() method: This is used to create and return a React element that represents the component's UI.
  • componentDidMount() method: This is run after the component has mounted into the DOM, allowing us to perform any necessary setup or fetch data from an API.
  1. Updating Phase: This is the time when the component is being re-rendered due to some change in its state or props.

During this phase, five lifecycle methods are called:
  • shouldComponentUpdate(nextProps, nextState): This is used to optimize the rendering process by determining if the component should re-render or not based on changes in its props or state.
  • render() method: This is called to create and return a new React element that represents the updated UI of the component.
  • getSnapshotBeforeUpdate(prevProps, prevState): This is used to capture a snapshot of the current props and state of the component before they are updated.
  • componentDidUpdate(prevProps, prevState, snapshot): This is run after the component has updated and allows us to perform any necessary side-effects, such as triggering animations or fetching data from an API.
  1. Unmounting Phase: This is the time when the component is being removed from the DOM.

During this phase, one lifecycle method is called:
  • componentWillUnmount(): This is called just before the component is unmounted from the DOM and allows us to perform any necessary cleanup tasks, such as removing event listeners or timers.

Overall, Lifecycle Methods in Class Components are a powerful tool to help you to understand and manage the lifecycle of your components.

March 25, 2023

7

#description

In a React app, components can be either functional or class-based. Class components are created using the class keyword and have Lifecycle methods. Lifecycle methods are special methods that are called at specific stages of a class-based component's life cycle, such as before it is mounted, when it is updated or when it is unmounted.

There are three categories of Lifecycle methods: Mounting, Updating, and Unmounting.

  1. Mounting Lifecycle Methods are called when an instance of a component is being created and inserted into the DOM.
  • constructor(): This method is called first, and it’s where you initialize the component. You can set the initial state, bind methods, or perform any other setup.
  • render(): This method is mandatory and returns the JSX markup/rendering of the class component.
  • componentDidMount(): This is called right after the component has been rendered on the page first time. It’s good for fetching data from APIs, updating react’s state using setState
  1. Updating Lifecycle methods are called when changes are being made to the component, such as new props being passed in, or when the state is changed.
  • shouldComponentUpdate(): This method is called before rendering, after the props or state are updated. Return a boolean value to determine whether the component should re-render or not.
  • render(): After the shouldComponentUpdate() method returns true, this method is called again to re-render the component with new values.
  • componentDidUpdate(): This method is called after the component's update is complete. This method can be used for side-effects or for interacting with the DOM.
  1. Unmounting Lifecycle Methods are called when the component is being removed from the DOM.
  • componentWillUnmount(): This method is called just before the component is removed from the DOM. You can perform any necessary cleanup, like clearing timers or removing event listeners.

With the help of Lifecycle methods, we can add additional functionality to our class components that can be used to manage the component data and interact with the DOM.

March 25, 2023

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