效果

问题总结

添加到body

this.$nextTick(() => {
  const body = document.querySelector('body')
  if (body.append) {
    body.append(this.$el)
  } else {
    body.appendChild(this.$el)
  }
})

禁止页面滚动

if (this.show) {
  document.body.style.height = '100vh'
  document.body.style['overflow-y'] = 'hidden'
} else {
  document.body.style.height = 'unset'
  document.body.style['overflow-y'] = 'auto'
}

切换页面或其他情况, 需要清除添加到body里的弹框

 destroyed () {
    // 如果被销毁, 则清除body里的dom
    if (this.appendBody && this.$el && this.$el.parentNode) {
      this.$el.parentNode.removeChild(this.$el)
    }
  }

组件源码

<template>
  <transition name="fade">
    <div class="b-popup" v-show="show">
      <transition name="b-fade">
        <div
          class="b-popup-mask"
          @click="close"
          v-show="hasMask && show">
        </div>
      </transition>
      <transition name="b-slide-up">
        <div
          v-show="show"
          class="b-popup-box b-slide-up"
          :class="contentPosition"
          :style="{background: popupBg, width: contentWidth, borderRadius: contentBorderRadius}">
          <div v-if="!noHeader" class="b-popup-header">
            <div class="iconfont icon-close" :class="closePosition" @click="close"></div>
            <div class="title">{{title}}</div>
          </div>
          <div class="b-popup-body">
            <slot name="body"></slot>
          </div>
        </div>
      </transition>
    </div>
  </transition>
</template>
<script>
export default {
  name: 'BPopup',
  props: {
    open: {
      type: Boolean,
      default: false
    },
    title: {
      type: String,
      default: '标题'
    },
    closePosition: {
      type: String,
      default: 'right'
    },
    noHeader: {
      type: Boolean,
      default: false
    },
    appendBody: {
      type: Boolean,
      default: true
    },
    popupBg: {
      type: String,
      default: '#fff'
    },
    hasMask: {
      type: Boolean,
      default: true
    },
    contentPosition: {
      type: String,
      default: 'bottom' // bottom, center, top
    },
    contentWidth: {
      type: String,
      default: '100%'
    },
    contentBorderRadius: {
      type: String,
      default: 'unset'
    }
  },
  model: {
    prop: 'open',
    event: 'update'
  },
  mounted () {
    if (this.appendBody) {
      this.$nextTick(() => {
        const body = document.querySelector('body')
        if (body.append) {
          body.append(this.$el)
        } else {
          body.appendChild(this.$el)
        }
      })
    }
    this.show = this.open
  },
  destroyed () {
    // 如果被销毁, 则清除body里的dom
    if (this.appendBody && this.$el && this.$el.parentNode) {
      this.$el.parentNode.removeChild(this.$el)
    }
  },
  data () {
    return {
      show: false
    }
  },
  methods: {
    close () {
      this.show = false
      this.$emit('update', false)
    }
  },
  watch: {
    open () {
      this.show = this.open
    },
    show () {
      if (this.show) {
        document.body.style.height = '100vh'
        document.body.style['overflow-y'] = 'hidden'
      } else {
        document.body.style.height = 'unset'
        document.body.style['overflow-y'] = 'auto'
      }
    }
  }
}
</script>
<style lang="scss" scoped>
.b-popup {
  position: fixed;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  z-index: 2;
  .b-popup-mask {
    position: fixed;
    top: 0;
    bottom: 0;
    left: 0;
    right: 0;
    pointer-events: auto;
    background-color: rgba(37,38,45,.7);
  }
  .b-popup-box {
    position: absolute;
    width: 100%;
    max-width: 100%;
    max-height: 100%;
    overflow: auto;
    text-align: center;
    font-size: 57px;
    // background: #fff;
    z-index: 2;
    &.center {
      left: 50%;
      top: 50%;
      transform: translate(-50%, -50%);
    }
    &.top {
      top: 0;
    }
    .b-popup-header {
      padding: 70px 0;
      position: relative;
      border-bottom: 2px solid #e0e0e0;
    }
    .icon-close {
      position: absolute;
      font-size: 70px;
      color: #b8b8b8;
      &.right {
        right: 40px;
      }
      &.left {
        left: 40px;
      }
    }
  }
  .b-fade {
    &-enter, &-leave-to {
      opacity: 0;
    }
    &-enter-active, &-leave-active {
      transition: opacity 250ms;
    }
  }
  .b-slide-up {
    &-enter, &-leave-to {
      transform: translate3d(0, 100%, 0);
    }
    &-leave-active, &-enter-active {
      transition: transform 300ms cubic-bezier(0.165, 0.84, 0.44, 1);
    }
  }
}

.fade-enter-active, .fade-leave-active {
  transition: opacity .5s;
}
.fade-enter, .fade-leave-to /* .fade-leave-active below version 2.1.8 */ {
  opacity: 0;
}
</style>