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Lecture 5 — React State

Objective:​

Learn state management techniques in React, including the use of hooks such as useState and useEffect, conditional rendering, list rendering, and updating arrays and objects in state. By the end, you will build a simple interactive To-do list with all data stored in the local state.

Duration:​

idk

5.1: Introduction to React State and useState​

Learning Goals:​

  • Understand the concept of state in React
  • Learn how to use the useState hook to manage state

Outline:​

  1. Understanding State in React

    • What is state?
    • Difference between props and state

  2. Using the useState Hook

    • Syntax and usage
    • Initial state and updating state

Activities:​

  • Create a simple counter using useState
  • Modify the counter to increase and decrease the count

Resources:​

5.2: Conditional Rendering with useState​

Learning Goals:​

  • Learn how to conditionally render components based on state

Outline:​

  1. Conditional Rendering

    • Using conditional statements in JSX
    • Ternary operators and logical &&

  2. Examples of Conditional Rendering

    • Show/hide elements based on state
    • Render different components based on state

Activities:​

  • Create a toggle button that shows/hides a message
  • Create a login/logout component that renders different content based on login state

Resources:​

5.3: Rendering Lists​

Learning Goals:​

  • Understand how to render lists in React
  • Learn the importance of keys in list rendering

Outline:​

  1. Rendering Lists

    • Mapping over arrays to create elements
    • Using the key prop

  2. Common Use Cases

    • Displaying a list of items
    • Rendering components based on array data

Activities:​

  • Create a component that renders a list of names
  • Enhance the component to render a list of objects with properties

Resources:​

5.4: Updating Arrays and Objects in State​

Learning Goals:​

  • Learn how to update arrays and objects in state
  • Understand immutability and why it’s important in React

Outline:​

  1. Updating Arrays in State

    • Adding, removing, and updating items in an array
    • Using the spread operator

  2. Updating Objects in State

    • Updating nested properties
    • Merging state updates

Activities:​

  • Create a component that allows adding and removing items from a list
  • Create a component that updates user profile information

Resources:​

5.5: Introduction to useEffect​

Learning Goals:​

  • Understand the purpose of the useEffect hook
  • Learn how to perform side effects in functional components

Outline:​

  1. Using the useEffect Hook

    • Syntax and basic usage
    • Cleaning up side effects

  2. Common Use Cases

    • Fetching data from an API
    • Subscribing to event listeners

Activities:​

  • Create a component that fetches data from an API and displays it
  • Create a component that updates the document title based on state

Resources:​

5.6: Building a Simple Interactive Todo List​

Learning Goals:​

  • Apply all learned concepts to build a simple Todo list application
  • Manage all data in the local state

Outline:​

  1. Project Overview

    • Introduction to the Todo list project
    • Understanding the project requirements and structure

  2. Building the Todo List

    • Setting up the initial state and UI
    • Adding new todos
    • Toggling todo completion status
    • Removing todos

  3. Review and Testing

    • Reviewing the completed project
    • Testing functionality

Activities:​

  • Build a Todo list application from scratch
  • Add features to add, toggle, and remove todos

Resources:​

Reading Material with Examples​

React State and useState​

// Counter.js
import React, { useState } from "react";

function Counter() {
  const [count, setCount] = useState(0);

  return (
    <div>
      <p>Count: {count}</p>
      <button onClick={() => setCount(count + 1)}>Increment</button>
      <button onClick={() => setCount(count - 1)}>Decrement</button>
    </div>
  );
}

export default Counter;