New Hooks API

Explain and implement a custom React hook using the new hooks API that includes features like auto-memoization or state grouping.

import { useState, useMemo } from 'react';

// Custom hook for auto-memoization
function useAutoMemoizedValue(calculation) {
  const [value, setValue] = useState(() => calculation());
  const memoizedValue = useMemo(() => calculation(), [calculation]);
  if (memoizedValue !== value) setValue(memoizedValue);
  return memoizedValue;
}

export default useAutoMemoizedValue;

This custom hook automatically memoizes a computed value based on a passed-in calculation function. useState is used to keep the current value, and useMemo re-computes the value when the calculation function changes. The hook then compares the memoized value with the current value and updates it if they differ, ensuring that the returned value is always up-to-date and auto-memoized.

import React from 'react';
import useAutoMemoizedValue from './useAutoMemoizedValue';

function App() {
  const expensiveComputation = () => {
    // Compute something expensive
    return Math.pow(10, 5);
  };

  const memoizedValue = useAutoMemoizedValue(expensiveComputation);

  return (
    <div>
      <p>Memoized Value: {memoizedValue}</p>
    </div>
  );
}

export default App;

This is an example of using the custom hook `useAutoMemoizedValue` within a React functional component. The hook is called with an expensive computation function, and the returned memoized value is rendered in the component.

body {
  font-family: 'Arial', sans-serif;
}
div {
  margin: 20px;
  padding: 10px;
  border: 1px solid #ddd;
  border-radius: 4px;
}
p {
  font-size: 16px;
  color: #333;
}

The accompanying CSS defines the styling for the application, including the font-family for the entire body, as well as margins, padding, border, border-radius, font-size, and color for div and p elements to make the rendered memoized value visually pleasing.