State variables in React, defined using the useState hook, can store various data types.

Below is a list of data types commonly used for state variables and their possible initial values:

1. Primitive Data Types

React state supports a range of primitive data types, which are the basic building blocks of data that represent a single value and are immutable. They include:

a. String: Store text values.

Initial Value: Typically an empty string or a specific text value.

Example:

    const [name, setName] = useState(''); 
    const [greeting, setGreeting] = useState('Hello');

b. Number: To store numeric values - integers or decimals.

Initial Value: Usually 0, any positive/negative number, or a floating-point value.

Example:

    const [count, setCount] = useState(0);
    const [price, setPrice] = useState(19.99);

c. Boolean: To track true/false states, such as toggles or conditions.

Initial Value: true or false.

Example:

    const [isLoggedIn, setIsLoggedIn] = useState(false); 
    const [isActive, setIsActive] = useState(true);

2. Complex Data Types

React state supports a range of complex data types, which are more intricate structures that can store multiple values or properties, and they are mutable.

a. Array: To store a list of items, such as strings, numbers, or objects.

Initial Value: An empty array or a prefilled array.

Example:

    const [items, setItems] = useState([]);
    const [fruits, setFruits] = useState(['apple', 'banana']); 

b. Object: To store key-value pairs or more structured data.

Initial Value: An empty object or a specific object.

Example:

    const [user, setUser] = useState({}); 
    const [profile, setProfile] = useState({name: 'John', age: 30});

3. Special Data Types

a. Null: To represent the absence of any value.

Initial Value: null.

Example:

    const [selectedItem, setSelectedItem] = useState(null); 

4. Function: To store a callable function as the state value.

Initial Value: A function definition or a placeholder (like () => {}).

Example:

    const [callback, setCallback] = useState(() => console.log('Hello'));

Choosing an initial value in the useState hook is context-driven, meaning the initial value should match the type of data you are working with.

For example:

• Use 0 for counters.
• Use null or an empty array/object for values that will be populated later.