React useThrottleCallback Hook Implementation

In React applications, frequently triggered events like scrolling or resizing can lead to performance issues if their associated callback functions are executed too often. This challenge asks you to implement a custom React hook, useThrottleCallback, that limits the rate at which a callback function can be invoked, improving performance and user experience.

Problem Description

You need to create a custom React hook named useThrottleCallback that takes a callback function and a throttle delay (in milliseconds) as arguments. This hook should return a memoized version of the callback function that, when called, will only execute the original callback at most once within the specified throttle delay. Subsequent calls to the throttled function within the delay period should be ignored.

Key Requirements:

• The hook must accept a callback function (callback) and a throttle delay (delay) as parameters.
• It should return a new function (the throttled callback) that replaces the original callback in your component's event handlers.
• The throttled callback should only execute the original callback function if the delay has passed since the last execution.
• The throttled callback should be stable across re-renders, meaning it should have a consistent reference unless the callback or delay changes.
• The throttled callback should correctly pass any arguments it receives to the original callback.

Expected Behavior:

When the throttled callback is invoked:

1. If enough time (delay) has passed since the last invocation of the original callback, the original callback is executed immediately with the provided arguments.
2. If not enough time has passed, the invocation is ignored.

Edge Cases to Consider:

• The initial invocation of the throttled callback should execute the original callback immediately.
• What happens if the delay is 0 or negative? (Assume a non-negative delay for practical purposes, but consider how your implementation handles it).
• The hook should re-calculate the throttled callback if either the original callback or the delay changes.

Examples

Example 1:

Scenario: A component has a button that, when clicked, increments a counter. We want to throttle these clicks so that the counter only increments once every 500ms, even if the button is rapidly clicked.

Input:

import React, { useState, useRef } from 'react';
import { useThrottleCallback } from './useThrottleCallback'; // Assuming hook is in this file

function CounterButton() {
  const [count, setCount] = useState(0);
  const buttonRef = useRef<HTMLButtonElement>(null);

  const increment = () => {
    setCount(prev => prev + 1);
    console.log('Incremented!');
  };

  const throttledIncrement = useThrottleCallback(increment, 500);

  return (
    <button ref={buttonRef} onClick={throttledIncrement}>
      Click Me (Throttled)
    </button>
  );
}

// In your application, you would render <CounterButton />

Expected Output (in console):

If the button is clicked rapidly for 2 seconds:

• "Incremented!" will appear roughly every 500ms. The total number of increments will be approximately (2000ms / 500ms) + 1 (for the initial click).

Explanation: The useThrottleCallback hook wraps the increment function. When the button is clicked, throttledIncrement is called. The first click executes increment immediately. Subsequent clicks within 500ms are ignored. After 500ms have passed since the last execution of increment, another click will trigger increment again.

Example 2:

Scenario: A component listens to window resize events. We want to update a state variable with the new dimensions, but only after a short delay to avoid excessive re-renders.

Input:

import React, { useState, useEffect } from 'react';
import { useThrottleCallback } from './useThrottleCallback'; // Assuming hook is in this file

function ResizeListener() {
  const [dimensions, setDimensions] = useState({ width: window.innerWidth, height: window.innerHeight });

  const updateDimensions = () => {
    setDimensions({ width: window.innerWidth, height: window.innerHeight });
    console.log('Dimensions updated:', window.innerWidth, window.innerHeight);
  };

  // Throttle the update function to execute at most once every 200ms
  const throttledUpdateDimensions = useThrottleCallback(updateDimensions, 200);

  useEffect(() => {
    window.addEventListener('resize', throttledUpdateDimensions);
    return () => {
      window.removeEventListener('resize', throttledUpdateDimensions);
    };
  }, [throttledUpdateDimensions]); // Dependency array includes the throttled callback

  return (
    <div>
      Width: {dimensions.width}, Height: {dimensions.height}
    </div>
  );
}

// In your application, you would render <ResizeListener />

Expected Output (in console):

When resizing the window rapidly:

• "Dimensions updated: [width] [height]" messages will appear at intervals of approximately 200ms, showing the latest window dimensions at those times. The displayed dimensions on screen will update accordingly.

Explanation: The resize event can fire very frequently. By using useThrottleCallback, we ensure that updateDimensions is only called when the browser has a moment to breathe, preventing performance degradation. The useEffect hook correctly re-attaches the listener if throttledUpdateDimensions changes (which it will if the original updateDimensions or delay changes).

Constraints

• The delay parameter will be a non-negative number representing milliseconds.
• The callback parameter will be a function that can accept any number of arguments.
• The hook must be implemented in TypeScript.
• Avoid using external libraries for throttling. Implement the logic yourself.
• The returned throttled callback must be stable and memoized using useCallback or equivalent, with appropriate dependencies.

Notes

• Consider using useRef to store the last execution timestamp and any pending timeouts.
• Remember to handle the case where the callback or delay dependencies change. The hook should re-initialize its internal state or logic accordingly.
• Think about how to ensure the throttled callback maintains its stable reference across re-renders using React hooks.