usePrevious custom hook for React

A lightweight and simple custom React hook that helps you track the previous value of a state or prop in your functional components.

Features

• Track Previous State: Easily keep track of the previous value of any piece of state or props in React.
• No Re-renders: Uses useRef to persist values across renders without triggering re-renders.
• Simple API: Provides an intuitive, easy-to-use API that seamlessly integrates with your existing React components.
• Lightweight: Minimal code that adds functionality without bloat.

Installation

Install the hook via npm:

npm install @gk3000/use-previous

or via yarn:

yarn add @gk3000/use-previous

##U sage

Basic Example

This hook is perfect for tracking the previous value of a piece of state or a prop in your component. Here's an example of how to use it in a functional component:

import React, { useState } from 'react';
import usePrevious from '@gk3000/use-previous';

function Counter() {
  const [count, setCount] = useState(0);
  
  // Track the previous value of the count state
  const previousCount = usePrevious(count);

  return (
    <div>
      <h1>Current Count: {count}</h1>
      <h2>Previous Count: {previousCount}</h2>
      <button onClick={() => setCount(count + 1)}>Increment</button>
      <button onClick={() => setCount(count - 1)}>Decrement</button>
    </div>
  );
}

export default Counter;

Parameters

const previousValue = usePrevious(value);

value (any): The state or prop value you want to track.

Returns

• previousValue: The previous value of the state or prop before the last update. On the initial render, it will return undefined.

Advanced Example

This hook can also track previous values of more complex data types, such as objects or arrays:

import React, { useState } from 'react';
import usePrevious from '@gk3000/use-previous';

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

  const previousUser = usePrevious(user);

  return (
    <div>
      <h1>Current User: {user.name}, Age: {user.age}</h1>
      <h2>Previous User: {previousUser?.name}, Age: {previousUser?.age}</h2>
      <button onClick={() => setUser({ name: 'Jane', age: 25 })}>
        Change User
      </button>
    </div>
  );
}

export default UserInfo;

Why Use usePrevious?

• Useful for Comparing State Changes: It helps in situations where you need to know the previous value to perform comparisons, animations, or transitions based on changes.
• Simple & Flexible: The hook is easy to use and works with any data type (primitives, arrays, objects).
• Optimized: Since usePrevious uses useRef, it stores the previous value without causing unnecessary re-renders, making it efficient for performance-sensitive components.

License

This project is licensed under the MIT License.