父页面

<template>
  <div style="margin-top: 20px">
    <div class="nav-style msg-style">
      <el-badge :value="value" :max="99" class="num" v-if="value > 0">
        <i class="el-icon-bell"></i>
      </el-badge>
      <i class="el-icon-bell" v-else></i>
      <message class="news-style" @getNums="getNumsFn"></message>
    </div>
  </div>
</template>
<script>
import message from './message.vue'
export default {
  components: { message },
  data() {
    return {
      value: 0
    }
  },

  methods: {
    getNumsFn(val) {
      this.value = val
    }
  }
}
</script>

<style scoped>
.el-icon-bell {
  font-size: 16px;
}

.nav-style label {
  text-align: center;
  width: 16px;
  height: 16px;
  position: absolute;
  top: 3px;
  right: 16px;
}

.nav-style .name {
  height: 22px;
  margin-top: 19px;
  margin-bottom: 19px;
  font-size: 14px;
  font-weight: 400;
  color: #24324c;
  line-height: 22px;
}

.msg-style {
  position: relative;
  float: right;
  margin-right: 100px;
}
.msg-style:hover .news-style {
  display: block;
}
.msg-style .num {
  line-height: 100%;
}
::v-deep .msg-style .el-badge__content {
  margin-top: 3px;
  padding: 0 3px;
  /* width: 28px; */
  min-width: 16px;
  height: 16px;
  background: #f2314e;
  text-align: center;
  line-height: 16px;
  font-size: 12px;
  z-index: 3;
}

.nav-style .el-button {
  font-size: 14px;
}
</style>

子页面（message.vue)

<template>
  <div class="news-style">
    <div class="msg">
      <div class="msg-header">消息中心</div>
      <div class="msg-style">
        <div v-if="msglist.length > 0">
          <div class="item" v-for="item in msglist" :key="item.id">
            <span class="blue dot"></span>
            <a
              :href="item.url"
              target="_blank"
              :class="[item.url ? 'title-style' : '', 'title']"
              v-bind:title="msglist.title"
            >
              <span @click="titleFn(item.id)" v-html="item.title"></span>
            </a>
          </div>
        </div>
        <div class="no-item" v-else>
          <span>暂无新消息，去别的地方看看吧~</span>
        </div>
      </div>
      <div class="msg-footer">
        <el-button type="text" @click="markFn" :disabled="msglist.length === 0"> 全部标为已读 </el-button>
        <!-- 跳转 -->
        <a class="link" target="_blank" rel="noreferrer" href="#/">查看全部 <i class="el-icon-arrow-right"></i> </a>
      </div>
    </div>
  </div>
</template>

<script>
export default {
  data() {
    return {
      msglist: [],
      isRead: false
    }
  },
  created() {
    this.informationFn() //信息
  },

  methods: {
    informationFn() {
      // 页面只能先展示2条
      const falselist = {
        num: 2,
        data: [
          {
            title: '宫1',
            id: 'c',
            url: 'https://fanyi.baidu.com/translate#en'
          },
          {
            title: '宫2',
            id: '0',
            url: 'https://www.baidu.com/'
          }
        ]
      }
      this.msglist = falselist.data ? falselist.data : []
      this.$emit('getNums', falselist.num)
    },

    markFn() {
      const ids = this.msglist.map(item => item.id)
      // 调接口
    },
    titleFn(id) {
      // 调接口
    }
  },
  beforeDestroy() {}
}
</script>

<style lang="scss" scoped>
.news-style {
  position: absolute;
  // top: 40px;//这个是为了固定的
  right: -10px;
  display: none;
  background-color: #fff;
  border-radius: 8px;
  box-shadow: 0px 8px 12px 4px rgba(0, 16, 47, 0.05);
  transition: all 0.3s;
}
.news-style .msg {
  position: relative;
  padding: 20px 0px 28px 28px;
  width: 356px;
  height: 313px;
  height: 230px;
}
.msg-header {
  margin-bottom: 25px;
  font-family: PingFangSC-Regular;
  font-size: 16px;
  font-weight: normal;
  line-height: 24px;
  color: #24324c;
}
.msg-style {
  overflow-y: scroll;
  margin-bottom: 64px;
  padding-right: 28px;
  .item {
    display: flex;
    justify-content: start;
    align-items: center;
    height: 40px;
    line-height: 40px;
    border-bottom: 1px solid rgba(#00102f, $alpha: 5%);
    .dot {
      display: inline-block;
      margin-right: 6px;
      min-width: 8px;
      height: 8px;
      border-radius: 50%;
    }
    .title {
      white-space: nowrap;
      overflow: hidden;
      text-overflow: ellipsis;
      font-family: PingFangSC-Regular;
      color: #24324c;
    }
    .title-style:hover {
      color: #2662ff;
    }
  }
  .item:last-child {
    border: 0;
  }
}
.msg-style .no-item {
  display: flex;
  justify-content: center;
  align-items: center;
  flex-direction: column;
  cursor: default;
  color: #8c93a1;
  img {
    margin: 10px 0 5px 0;
  }
}
.msg-style .item .red {
  background: #ff5959;
}
.msg-style .item .org {
  background: #ff8800;
}
.msg-style .item .blue {
  background: #5987ff;
}
.msg-footer {
  position: absolute;
  bottom: 0;
  margin-bottom: 28px;
  display: flex;
  justify-content: space-between;
  width: 300px;
  line-height: 22px;
  img {
    vertical-align: bottom;
  }
  .link {
    margin-top: 9px;
    color: #2662ff;
  }
  ::v-deep .el-button {
    font-family: PingFangSC-Regular;
    font-size: 14px;
    font-weight: normal;
    color: rgba(0, 16, 47, 0.65);
  }
  ::v-deep .el-button--text.is-disabled {
    color: #bfc3cb;
  }
}
</style>