taro makes a virtual list based on page scroll events

Implementing Virtual Lists with Page Scroll in Taro Framework. Explores a technique for optimizing the rendering of large data lists by only displaying visible items. Discusses the built-in VirtualList component in Taro and provides performance optim

How to Implement a Virtual List Based on Page Scroll Event in Taro

A virtual list is a technique used to render large lists of data efficiently by only rendering the visible items and recycling the DOM elements as the user scrolls. This improves performance by reducing the number of DOM elements that need to be rendered and manipulated.

To implement a virtual list based on page scroll event in Taro, you can follow these steps:

1. Track the scroll position of the list container.
2. Calculate the index of the first visible item based on the scroll position and item height.
3. Render only the visible items, starting from the first visible item.
4. As the user scrolls, update the first visible item index and render the new set of visible items.

Does Taro Have a Ready-to-Use Virtual List Component?

Yes, Taro has a built-in virtual list component called VirtualList. To use it, you can import it like this:

<code class="javascript">import { VirtualList } from '@tarojs/components';</code>

And then use it like this:

<code class="javascript"><VirtualList
  height={500}
  itemSize={50}
  data={['Item 1', 'Item 2', 'Item 3', ...]}
  renderItem={(item) => <View>{item}</View>}
/></code>

Performance Optimization Tips for Virtual Lists

When implementing virtual lists, it is important to consider performance optimization techniques to ensure a smooth and responsive user experience. Here are some tips:

• Use a fixed item height: This allows the calculation of the first visible item index to be done more efficiently.
• Avoid using nested virtual lists: This can lead to performance issues as the inner virtual list will constantly need to re-render when the outer virtual list scrolls.
• Use windowing techniques: This involves rendering only a subset of the visible items at a time, which can reduce the number of DOM elements that need to be manipulated.
• Implement lazy loading: This involves loading the data for items that are about to become visible, rather than loading all the data upfront.
• Use a key extractor: This is used to provide a unique identifier for each item, which allows the virtual list to efficiently update and recycle DOM elements.

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