Building a Time-Slicing Renderer in React

This challenge focuses on implementing a basic time-slicing rendering mechanism in React using TypeScript. Time-slicing is a technique used to break down long-running, computationally intensive tasks into smaller chunks that can be executed over multiple render cycles. This prevents the main thread from blocking, leading to a more responsive user interface, especially when dealing with large datasets or complex rendering logic.

Problem Description

Your task is to build a React component that renders a list of items, but instead of rendering all items at once, it should render them incrementally over time. This simulates a time-slicing renderer where the rendering of a large list is "sliced" into smaller, manageable chunks.

Key Requirements:

1. Component Structure: Create a React functional component named TimeSlicingList that accepts a items prop (an array of any type).
2. Incremental Rendering: The component should render the items array in batches. Each batch should be rendered after a short delay, allowing the browser to perform other tasks.
3. Controlled Batch Size: Allow the user to configure the number of items rendered in each batch. This should be a prop named batchSize.
4. Progress Indication (Optional but Recommended): Display some indication of rendering progress, such as the number of items rendered so far.
5. Completion Notification: Once all items are rendered, indicate that the rendering is complete.
6. TypeScript: All code should be written in TypeScript, ensuring type safety.

Expected Behavior:

When TimeSlicingList receives a large array of items, it should not render them all in a single paint. Instead, it should render the first batchSize items, then pause briefly, render the next batchSize items, and so on, until all items are displayed. The UI should remain interactive during this process.

Edge Cases:

• Empty items array: The component should handle an empty list gracefully, perhaps by rendering nothing or a message.
• batchSize larger than items.length: In this case, all items should be rendered in a single batch (effectively no time-slicing needed).
• Rapid updates to items: Consider how the component should behave if the items prop changes frequently. For this challenge, assume the items prop is relatively stable after the initial render, or that a re-render of the component will restart the time-slicing process.

Examples

Example 1: Rendering a list of numbers

Input:
items = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
batchSize = 3

Expected Output (Visualized):

Initially, nothing is rendered.

After a short delay:

<div>
  Rendering: 3 / 10
  <ul>
    <li>1</li>
    <li>2</li>
    <li>3</li>
  </ul>
</div>

After another short delay:

<div>
  Rendering: 6 / 10
  <ul>
    <li>1</li>
    <li>2</li>
    <li>3</li>
    <li>4</li>
    <li>5</li>
    <li>6</li>
  </ul>
</div>

After another short delay:

<div>
  Rendering: 10 / 10
  <ul>
    <li>1</li>
    <li>2</li>
    <li>3</li>
    <li>4</li>
    <li>5</li>
    <li>6</li>
    <li>7</li>
    <li>8</li>
    <li>9</li>
    <li>10</li>
  </ul>
  <p>Rendering complete!</p>
</div>

Explanation: The component renders the first 3 items, then the next 3, and finally the remaining 4. A progress indicator shows the current rendering status.

Example 2: Empty list

Input:
items = []
batchSize = 5

Expected Output: (Component renders nothing, or a "No items to display" message)

Explanation: No items to render, so nothing is shown.

Example 3: batchSize larger than list

Input:
items = ["apple", "banana"]
batchSize = 10

Expected Output (Visualized after one delay):

<div>
  Rendering: 2 / 2
  <ul>
    <li>apple</li>
    <li>banana</li>
  </ul>
  <p>Rendering complete!</p>
</div>

Explanation: Since batchSize is greater than the total number of items, all items are rendered in a single batch.

Constraints

• The items prop will be an array of any type.
• batchSize will be a positive integer.
• The maximum number of items in a list can be up to 10,000.
• The delay between batches should be in the range of 10ms to 100ms.
• The component should not block the main thread for more than 10ms at a time during rendering.

Notes

• You will likely need to use React Hooks such as useState, useEffect, and potentially useRef to manage the state of your rendering process and to schedule the rendering of batches.
• Consider using requestAnimationFrame or setTimeout with a small delay to achieve the time-slicing effect.
• The goal is to simulate a performant rendering of large lists, not necessarily to implement a fully optimized production-ready solution. Focus on the core concept of breaking down work.
• For the "Rendering: X / Y" part, you can simply display the count of currently rendered items versus the total items.