从底部弹出来，有过渡动画效果

用max-height可以自适应内容的高度，当内容会超过最大高度时可以在弹窗里加个scroll-view
弹窗不能用v-if来隐藏，不然transition没效果，transition只能对已有dom元素起效果，所以用透明和visibility来隐藏

<view @tap="showpop">弹出来</view><view class="popWai" :class="isshowpop?'popWaiAc':''" @tap="closepop"><view class="popNei" :style="isshowpop?'bottom:0':'bottom:-680rpx'"><div>发顺丰萨芬撒</div></view>
</view>

data(){return{isshowpop:false,}
},
methods:{showpop(){this.isshowpop = true;},closepop(){this.isshowpop = false;},
}

.popWai{position: fixed;top: 0;left: 0;background-color: rgba(0, 0, 0, 0.5);width: 100%;height: 100%;z-index: 99;opacity: 0;visibility: hidden;overflow: hidden;
}
.popNei{position: absolute;left: 0;width: 100%;max-height: 680rpx;background-color: #fff;transition: all 0.5s ease-out;
}
.popWaiAc {opacity: 1;visibility: visible;
}