How to use scrpll-view component to implement pull-down refresh in uniapp

How to use the scrpll-view component to implement pull-down refresh in uniapp? The following article will introduce to you how to use scroll-view to customize pull-down refresh in uniapp. I hope it will be helpful to you!

uniapp pull-down refresh

There are two methods for pull-down refresh in uniapp, one is the overall pull-down refresh, Use the page life cycle function onPullDownRefresh; the other is local pull-down refresh, also called custom pull-down refresh, using the custom pull-down refresh event in the scrpll-view component.

1. Refresh the entire page (onPullDownRefresh)

Define the onPullDownRefresh processing function in js (and onLoad, etc. Lifecycle function sibling), listen to the user pull-down refresh event of the page. [Official Document]No more introduction here! Today’s focus is below

2. Customized page refresh (scroll-view)

Encountered in the component The problem

• #cannot trigger the drop-down (cause troubleshooting)

  1. The scroll-view component is not wrapped with a view. Although the official website does not mention this problem, If there is no external view that wraps this component alone, there is no way to trigger events in the scroll-view component.

  2. The scroll-view does not have a fixed height. Set the height in CSS. The height will be displayed in the area. For example, if the height is set to 50vh (100vh is full screen), the content inside the component will be displayed. It will only scroll up and down in half the screen. It will not trigger the scroll bar of the page. It will only trigger the scroll bar of scroll-view. If it is difficult to determine the height, you can use scss(lang=' The calc calculation in scss') is reflected in the example. (Note that when using calc calculation, there must be spaces around -).

  3. If the high is set as a percentage, the drop-down cannot be triggered. You can use max-hight for high, but you cannot use min-hight.

  4. No scroll-y is set

• Does not scroll to the top to trigger the drop-down, but triggers the drop-down in the visible page

  Official default no matter Wherever the scroll bar of the page is, as long as you scroll up or down on the scroll-view page, the drop-down function will be triggered, which makes the user experience very poor. You can use the @scroll function that is triggered when scrolling to obtain the scroll-view The position of the scroll bar, and then control refresher-enabled to turn on and off custom pull-down refresh. When the scroll bar of scroll-view scrolls to the top, enable refresher-enabled is true, and other conditions are false.
  

Go directly to the code to see: html:

<template>
<view>
  <scroll-view
    show-scrollbar="true"
    style="height: 300px"
    scroll-y="true"
    :refresher-enabled="isOpenRefresh"
    :refresher-triggered="triggered"
    :refresher-threshold="100"
    refresher-background="gray"
    @refresherpulling="onPulling"
    @refresherrefresh="onRefresh"
    @refresherrestore="onRestore"
    @refresherabort="onAbort"
    @scroll="onScroll"
  >
  <view v-if="!isOpenRefresh">别拉了，没有更多了~</view>
  <view class="item" v-for="(item, index) in dataList" :key="index">{{ item }}</view>
  </scroll-view>
</view>
</template>

Basically, these are the only attribute methods used for pull-down refresh! js:

export default {
  data() {
    return {
      triggered: false,
      dataList: [],
      arr: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30],
      page: 0,
      isOpenRefresh: true // 是否开启下拉
    };
  },
  onLoad() {
    this._freshing = false;
    this.getData()
  },
  methods: {
    dealArray(array, groupNum) {
      let temp = [];
      for (let i = 0, len = array.length; i < len; i += groupNum) {
        temp.push(array.slice(i, i + groupNum));
      }
      return temp;
    },
    // 自定义下拉刷新控件被下拉
    onPulling(e) {
      console.log("onpulling", e);
      if (e.detail.deltaY < 0) return  // 防止上滑页面也触发下拉
      this.triggered = true;
    },
    // 自定义下拉刷新被触发
    onRefresh() {
      if (this._freshing) return;
      this._freshing = true;
      this.page++;
      setTimeout(() => {
        this.triggered = false;
        this._freshing = false;
        this.getData();
      }, 500);
    },
    // 自定义下拉刷新被复位
    onRestore() {
      this.triggered = &#39;restore&#39;; // 需要重置
      console.error("onRestore");
    },
    // 自定义下拉刷新被中止
    onAbort() {
      console.error("onAbort");
    },
    getData() {
      // 前端模拟分页
      let temp = this.dealArray(this.arr, 3) 
      if (this.page > temp.length - 1) {
        this.isOpenRefresh = false
        return 
      }
      this.dataList.push(...temp[this.page])
    }
  },
};

style:

<style>
view {
  text-align: center;
}
.item:nth-child(odd) {
  background-color: antiquewhite;
}
.item:nth-child(even) {
  background-color: aquamarine;
}
</style>

[Note] The scroll-view pull-down refresh will cause the page to slide up and trigger the pull-down. You can do this in @refresherpulling="onPulling"This method is as followsif (e.detail.deltaY // Prevent the page from sliding up and triggering the dropdown too

Demonstration:

appears. As long as you slide the page down anywhere on the page, the drop-down will be triggered. This type of problem occurs. You can use @scrolltoupper="scrolltoupper"Topping function, making an admission in it can solve the problem!

// 触顶操作-准入
scrolltoupper() {
    this.isAllowRefresh = true
}

// 自定义下拉刷新控件被下拉

onPulling(e) {
    if (e.detail.deltaY < 0) return
    if (!this.isAllowRefresh) return;
    this.isRefresh = true;
    console.log("onpulling", e);
}

You can also use @scroll="onScroll" to monitor the value of scroll-top and make it ===0 Triggered when , that is, reaching the top! Trigger again! But when he encounters it, he has to slide the page and the scroll bar will appear, and he will listen! We can initialize it during init so that its variables are initially 0!

export default class Index extends mixins(uiMixin) {
	scrollTop: number = 0
	// 监听页面是否滚动 
	onScroll(e) {  
      this.scrollTop = e.detail.scrollTop
	}
	// 自定义下拉刷新被触发
  onRefresh() {
	if (this.scrollTop === 0) {
		if (this._freshing) return;
        this._freshing = true;
        this.page++;
       	setTimeout(() => {
          this.triggered = false;
          this._freshing = false;
          this.getData();
       }, 500);
	}
  }
})

Recommended: "uniapp tutorial"

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