intersection-observer.vue
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<template>
<view>
<page-head :title="title"></page-head>
<view class="uni-padding-wrap uni-common-mt">
<view class="uni-title uni-common-mt">
{{appear ? '小球出现' : '小球消失'}}
</view>
<scroll-view class="scroll-view" scroll-y>
<view class="scroll-area">
<text class="notice">向下滚动让小球出现</text>
<view class="ball"></view>
</view>
</scroll-view>
</view>
</view>
</template>
<script>
let observer = null;
export default {
data() {
return {
appear: false,
title:'intersectionObserver'
}
},
onReady() {
observer = uni.createIntersectionObserver(this);
observer.relativeTo('.scroll-view').observe('.ball', (res) => {
if (res.intersectionRatio > 0 && !this.appear) {
this.appear = true;
} else if (!res.intersectionRatio > 0 && this.appear) {
this.appear = false;
}
})
},
onUnload() {
if (observer) {
observer.disconnect()
}
}
}
</script>
<style>
.scroll-view {
height: 400rpx;
background: #fff;
border: 1px solid #ccc;
box-sizing: border-box;
}
.scroll-area {
height: 1300rpx;
display: flex;
flex-direction: column;
align-items: center;
}
.notice {
margin-top: 150rpx;
margin: 150rpx 0 400rpx 0;
}
.ball {
width: 200rpx;
height: 200rpx;
background: #4cd964;
border-radius: 50%;
}
</style>