Custom function like useState Hook

function userProfile() {
  let user = {
    name: "",
    age: 0,
    email: "",
  };

  function setUser(name, age, email) {
    user.name = name;
    user.age = age;
    user.email = email;
  }

  function getUserData() {
    return user;
  }

  return [getUserData, setUser];
}

const [userData, setUser] = userProfile();

setUser("John Doe", 30, "johndoe@example.com");

console.log("User Data:", userData());
// Output: User Data: { name: 'John Doe', age: 30, email: 'johndoe@example.com' }

// You can also update user data using setUser
setUser("Alice Smith", 25, "alice.smith@example.com");

console.log("Updated User Data:", userData());
// Output: Updated User Data: { name: 'Alice Smith', age: 25, email: 'alice.smith@example.com' }

In this example:

• The userProfile function initializes a user object with properties like name, age, and email.

• It returns an array with two elements:

  • getUserData: Returns the current user data.

  • setUser: Allows you to set user data.

You can invoke userProfile() to create an instance, set user data using setUser, and retrieve user data using userData(). This demonstrates the desired syntax you mentioned.

Creating a similar function

Creating a function similar to useState for your custom library called useFunc would involve implementing a state management mechanism that allows components to manage and update their state. Below is a simple example of how you can create a useFunc function that mimics the behavior of useState:

// Your custom library - useFunc.js

// Create a variable to store the state and a function to update it.
let state;
let setStateCallbacks = [];

function useState(initialValue) {
  if (typeof state === 'undefined') {
    state = initialValue;
  }

  const currentIndex = setStateCallbacks.length;

  const setState = (newValue) => {
    state = newValue;
    setStateCallbacks.forEach((callback, index) => {
      if (index !== currentIndex) {
        callback(state);
      }
    });
  };

  setStateCallbacks.push(setState);

  return [state, setState];
}

function useFunc(initialValue) {
  return useState(initialValue);
}

export default useFunc;

In this example, we have useState that manages the state and provides a function to update it. We also have a global array setStateCallbacks to keep track of all the state update functions.

The useFunc function simply wraps useState, allowing you to use it in a way similar to useState:

// Your component - MyComponent.js

import useFunc from 'useFunc';

function MyComponent() {
  const [count, setCount] = useFunc(0);

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

export default MyComponent;

Now you can use useFunc in your components to manage state just like you would with useState from the React library. Remember that this is a simplified example, and the actual implementation of state management in React is more complex and handles various edge cases and optimizations. Depending on your use case, you might want to expand upon this example to handle more advanced scenarios.

Converting the userProfile function into a functional component

Converting the userProfile function into a functional component using the useState hook, you can follow this example:

import React, { useState } from 'react';

function UserProfile() {
  // Initialize user state with default values
  const [user, setUser] = useState({
    name: "",
    age: 0,
    email: "",
  });

  // Function to update user data
  const updateUser = (name, age, email) => {
    setUser({
      ...user, // Preserve existing user properties
      name: name,
      age: age,
      email: email,
    });
  };

  return (
    <div>
      <h1>User Profile</h1>
      <p>Name: {user.name}</p>
      <p>Age: {user.age}</p>
      <p>Email: {user.email}</p>

      <button onClick={() => updateUser("John Doe", 30, "johndoe@example.com")}>
        Set User Data
      </button>

      <button onClick={() => updateUser("Alice Smith", 25, "alice.smith@example.com")}>
        Update User Data
      </button>
    </div>
  );
}

export default UserProfile;

In this code:

1. We import React and useState from the React library.

2. We define the UserProfile functional component.

3. Inside the component, we use the useState hook to initialize the user state with default values.

4. We define the updateUser function to update the user data, merging the new data with the existing state using the spread operator (...user).

5. Within the component's JSX, we display the user's name, age, and email.

6. We provide buttons to set and update the user data, which trigger the updateUser function with the desired values.

This code converts your original userProfile function into a React functional component that uses the useState hook to manage and display user data.