React Lifecycle in 4 Minutes

Mastering the React lifecycle is the first step to debugging like a pro.

Here’s an easy 4-minute guide.

What Is the React Component Lifecycle?

A React component is like a human being. Born, evolve, and die. React components follow a lifecycle: they’re born (mounting), they update, and then they die (unmounting).

Mounting: React creates the component and adds it to the DOM.
Updating: The component changes in response to state changes.
Unmounting: React removes the component and cleans up resources.

Why Do You Need To Understand React Component Lifecycle?

Understanding the React lifecycle helps you write better effects with useEffect and useLayoutEffect, avoid inefficiencies, prevent memory leaks, and optimize performance.

The Three Phases of the React Component Lifecycle

1. Mounting: When a Component Is First Rendered

Mounting occurs when React adds a component to the screen. Triggered by root.render(<MyComponent />) or when React adds a component to the JSX tree.

Mounting process: Render, Insert DOM Nodes, Set DOM Refs, Run useLayoutEffect, DOM Paint, Run useEffect.

2. Updating: When a Component Re-Renders

Updating happens when React re-renders a component to reflect changes. Triggered by state updates, context changes, parent re-rendering, etc.

Updating process: Re-render, Reconciliation, Commit Changes, Unset DOM Refs, Cleanup useLayoutEffect, Set DOM Refs, Run useLayoutEffect, Paint the DOM, Cleanup useEffect, Run useEffect.

3. Unmounting: When React Removes a Component

Unmounting occurs when React removes a component from the DOM. Triggered when a component is no longer in the JSX tree, parent unmounts, or the component’s key changes.

Unmounting process: Run Cleanup Functions, Unset DOM Refs, Remove DOM Nodes.

Additional Resources To Go Further

Summary

Three phases: mounting, updating, and unmounting. unmounting.

Start practicing these concepts with real-world examples:

Use useLayoutEffect for DOM measurements.
Always clean up effects when a component unmounts.

You’ve got this 💪.

React Lifecycle in 4 Minutes

A quick overview of the React component lifecycle.