Optimization strategy for UniApp to implement pull-down refresh and pull-up loading

UniApp is a framework that supports multi-terminal development. It can use a set of codes to develop applications that adapt to multiple platforms at the same time. During the development process using UniApp, pull-down refresh and pull-up loading functions are one of the common requirements. In order to improve the user experience, it is very important to optimize the performance of these two functions. This article will introduce several optimization strategies to make UniApp’s pull-down refresh and pull-up loading smoother.

1. Pull-down refresh optimization strategy
Pull-down refresh is an operation in which the user slides on the page and pulls down the page to refresh the data. The performance optimization of the pull-down refresh function mainly includes two aspects: the smoothness of the refresh animation and the speed of data update.

1. Use CSS animation
   UniApp implements the pull-down refresh animation effect by using CSS animation. Define the animation effect required for pull-down refresh in the css file, and use @keyframes rules to control the number of frames and frame changes of the animation. This can avoid using JavaScript for animation processing and improve the smoothness of animation.

Sample code:

@keyframes refresh {
  0% {
    transform: rotate(0deg);
  }
  100% {
    transform: rotate(360deg);
  }
}

.refresh-icon {
  animation: refresh 1s linear infinite;
}

When using the drop-down refresh component in the <template> tag, just add the corresponding class name to the refresh icon.

2. Throttling and anti-shake
   Due to the fast sliding speed of the user, pull-down refresh events may be triggered frequently. In order to reduce the refresh frequency, you can use throttling and anti-shake methods. In Vue, you can use the lodash library to achieve throttling and anti-shake.

Sample code:

import { throttle } from "lodash";

export default {
  data() {
    return {
      isRefreshing: false
    };
  },
  methods: {
    onPullDownRefresh: throttle(function() {
      if (this.isRefreshing) {
        return;
      }
      this.isRefreshing = true;
      // 执行刷新操作
      ...
      // 模拟请求数据，延迟500毫秒
      setTimeout(() => {
        this.isRefreshing = false;
      }, 500);
    }, 1000)
  }
}

When using the pull-down refresh component in the <template> tag, bind the @refresh event that is Can.

2. Pull-up loading optimization strategy
Pull-up loading is an operation in which the user slides on the page and automatically loads more data when sliding to the bottom. The performance optimization of the pull-up loading function mainly includes two aspects: the smoothness of the loading animation and the loading speed of the data.

1. Use CSS animation
   Similar to pull-down refresh, the pull-up loading animation effect is achieved by using CSS animation. You can use the @keyframes rules to define the change process of the loading animation, and then when using the pull-up to load the component in the <template> tag, just add the corresponding class name to the loading icon.
2. Paging loading
   In order to improve the data loading speed of pull-up loading, paging loading can be used. That is, when sliding to the bottom, only the next page of data is loaded instead of loading all the data at once. This can reduce the overhead of loading large amounts of data at one time and improve loading speed.

Sample code:

export default {
  data() {
    return {
      isLoadingMore: false,
      page: 1,
      pageSize: 10,
      dataList: []
    };
  },
  methods: {
    onLoadMore() {
      if (this.isLoadingMore) {
        return;
      }
      this.isLoadingMore = true;
      // 执行加载操作
      ...
      // 模拟请求数据，延迟500毫秒
      setTimeout(() => {
        // 添加新的数据到dataList中
        ...
        this.page++;
        this.isLoadingMore = false;
      }, 500);
    }
  }
}

When using pull-up to load components in the <template> tag, bind the @loadmore event That’s it.

This article introduces the optimization strategy of UniApp pull-down refresh and pull-up loading. By using CSS animation, throttling and anti-shake, and paging loading, the fluency and speed of pull-down refresh and pull-up loading can be improved. I hope this article will be helpful to UniApp developers.

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