DEV Community

Cover image for Advanced React Insights: Deep Dive into Key Concepts
bilel salem
bilel salem

Posted on • Updated on

Advanced React Insights: Deep Dive into Key Concepts

Hello Everyone,السلام عليكم و رحمة الله و بركاته

I hope you are well. While reading the React Interview Guide by Sudheer Jonna and Andrew Baisden, many advanced concepts caught my eye. I want to share these advanced insights with you, and إن شاء الله, we will discuss each concept in detail in individual articles.

Memoization and Component Optimization

  1. memo:

    • Purpose: Optimizes functional components by making a shallow comparison between the old props and the new props. Prevents re-rendering if props haven't changed.
    • Usage: React.memo(Component).
  2. PureComponent:

    • Purpose: Similar to memo, but for class components. Automatically performs a shallow comparison of props and state to prevent unnecessary re-renders.
    • Usage: Extend React.PureComponent.

Component Enhancement Techniques

  1. Higher Order Component (HOC):

    • Definition: A function that takes a component and returns a new component with additional props or behavior.
    • Example:
     const withHigherOrderComponent = (OriginalComponent) => (props) => <OriginalComponent {...props} />;
  2. Fragments:

    • Purpose: Allow grouping of multiple elements without adding extra nodes to the DOM, which can improve performance.
    • Usage: <React.Fragment> or the shorthand <>.

Default Props and State Management

  1. defaultProps:

    • Purpose: Define default values for props if none are provided.
    • Usage:
     Employee.defaultProps = {
       name: "Jack",
       age: 45,
       department: "HR"
  2. Updating Nested State:

    • Technique: Spread syntax to update deeply nested state properties without mutating the original state.
    • Example:
       address: {
         postalCode: 75015

State and Effect Hooks

  1. useReducer:

    • Purpose: Manage complex state logic and optimize performance for components with nested updates.
    • Usage:
     const [state, dispatch] = useReducer(reducer, initialState);
  2. useContext:

    • Purpose: Access the value of a context at any nesting level. There is no restriction on the number of times you can override the context.
    • Usage:
     const value = useContext(MyContext);
  3. useEffect:

    • Purpose: Handle side effects in functional components, such as fetching data or updating the DOM.
    • Usage:
     useEffect(() => {
       // Effect logic
       return () => {
         // Cleanup logic
     }, [dependencies]);
  4. useLayoutEffect:

    • Purpose: Similar to useEffect, but fires synchronously after all DOM mutations and before the browser repaints.
    • Usage:
      useLayoutEffect(() => {
        // Effect logic
      }, [dependencies]);
  5. useInsertionEffect:

    • Purpose: Fire before React makes changes to the DOM, such as adding dynamic CSS.
    • Usage:
      useInsertionEffect(() => {
        // Effect logic
      }, [dependencies]);

Performance and Rendering

  1. flushSync:

    • Purpose: Flush pending state updates and force a re-render from inside an event handler or an effect.
    • Usage:
      const handleAddTodo = (todoName) => {
        flushSync(() => {
          setTodos([...todos, { id: uuid(), task: todoName }]);
        todoListRef.current.scrollTop = todoListRef.current.scrollHeight;
- **Warning**: Can negatively impact performance if overused.
Enter fullscreen mode Exit fullscreen mode
  1. Reconciliation:

    • Definition: The process of comparing two virtual DOM trees and determining how to efficiently update the real DOM.
    • Mechanism: React uses a diffing algorithm to minimize changes to the real DOM.
  2. Virtual DOM:

    • Purpose: An abstraction that React uses to optimize updates to the real DOM.
    • Mechanism: Changes are computed in the virtual DOM and then applied selectively to the real DOM.
  3. React Fiber:

    • Definition: A reimplementation of the React reconciliation algorithm introduced in React 16, designed for modern web browsers.
    • Purpose: Improves responsiveness and user experience by breaking rendering work into smaller units.


  1. Refs:

    • Purpose: Access DOM nodes or React elements created in the render method.
    • Usage:
      const myRef = useRef(null);
  2. useImperativeHandle:

    • Purpose: Customize the instance value that is exposed when using ref in a parent component.
    • Usage:
      useImperativeHandle(ref, () => ({
        customMethod() {
          // Custom logic
  3. Synthetic Events:

    • Definition: Cross-browser wrapper around native browser events.
    • Purpose: Ensure consistent event behavior across different browsers.

By leveraging these tips and techniques, you can optimize your React applications for better performance, maintainability, and scalability. Understanding and applying these concepts will help you build more efficient and robust React components.


I will inche Allah post articles about the New technologies such React 19 and Next 15 but i need to cover essentials first then i could deeply dive into World of news .

Top comments (3)

madhan_s profile image
Madhan S

Nice Compilation 👏.
defaultProps for function component has been deprecated and will be removed in React 19. Source. Alternate is to use ES6 default parameters

ali_ab24_60e2683aad1437fe profile image
ali AB24

keep up the good work !

faroukabichou profile image
Farouk Abichou

Keep going!