ReactJS
Reconciliation in React
Need technical help?
Our experts will get back to you within 24 hours.
Reconciliation in React is a core concept that guarantees efficient updating of the UI upon change of application state or props. Techniques like Virtual DOM and diffing algorithms allow it to optimize rendering performance so that the user experience is fluid and event-driven. This article delves into how reconciliation works in React with related techniques and best practices to boost performance.
What is reconciliation?
Reconciliation in React is the process that determines how many changes need to be done to the User Interface(U.I) whenever the data or state of a component changes.
Reconciliation in React
Understanding Reconciliation in React:
Virtual DOM and Rendering:
The Virtual DOM plays a very important role in the reconciliation process. Instead of manipulating the real DOM directly, React creates a lightweight representation, or so-called virtual DOM. As data changes, React first updates the virtual DOM rather than the real one.
Diffing Algorithm
The diffing algorithm works by comparing the virtual DOM of the previous component tree to the updated virtual DOM. From the root of the virtual DOM, it continues to check down each node until all nodes are checked. Finally, it will selectively update, insert, or remove nodes in the actual DOM based on detected changes.
Whenever the differences are found, React updates the real DOM to mirror the new state of the application. React does this in a manner that precludes unnecessary re-rendering of components and ensures that only the parts of the UI that have been affected are updated.
Key Steps in the Diffing Algorithm
Use Keys for Lists: When rendering dynamic lists of components (map() function or similar), always provide a unique key prop to each item. This allows React to identify each item uniquely and optimize updates. Keys should be stable, predictable, and ideally unique among siblings.
{items.map(item => ( <ListItem key={item.id} item={item} />))} Keep Component Hierarchies Shallow:The component tree should be as shallow as possible. The more complex the component hierarchies, the slower reconciliation may get, since React would have to perform more nodes traversal to figure out what has changed. Break apart complex components into smaller, more conceivable parts.
Use React.memo:React.memo (Functional Components): Memoizes the result of the component rendering based on its props. It prevents re-rendering if props haven't changed. Use it for functional components to optimize performance.
const MyComponent = React.memo(function MyComponent(props) { return <div>{props.value}</div>;});
Batch State Updates:When one is updating based on previous state or doing multiples of state update within a function, use function form of setState. React would automatically batch multiple state updates through the function forms, which eliminates unnecessary renders thus improving performance
const incrementCounter = () => { setCounter(prevCounter => prevCounter + 1); setAnotherState(prevState => ({ ...prevState, key: 'value' }));};Avoid Inline Functions in Render:Avoid Inline Functions in Render: Define event handlers outside of the render method to avoid creating new function instances on every render. This helps in performance by reducing unnecessary re-renders due to prop changes.
function handleClick() { // handle click logic}function MyComponent() { return <button onClick={handleClick}>Click me</button>;} Memoize Expensive Computations: Memoization techniques such as caching results of expensive computations using libraries like memoize-one can optimize performance by avoiding repeated calculations across renders.
import memoize from 'memoize-one';const calculateExpensiveValue = memoize((a, b) => { // perform expensive computation based on a and b return result;});Conclusion:
Virtual DOM: React keeps a virtual copy of the DOM in memory.
Diffing Algorithm: Compares the previous and updated virtual DOMs to minimize DOM updates.
Key Prop: Use key prop in lists to optimize item identification and updates.
Efficiency: Reduces performance overhead by updating only changed DOM elements.
Component Reusability: Supports modular design and efficient updates across component hierarchies.
Optimisations: Techniques such as using PureComponent, React.memo and batched state updates, improve performance.
Declarative UI development and no focus on manual DOM manipulation.
Ready to transform your business with our technology solutions? Contact Us today to Leverage Our ReactJS Expertise.
0
React
