vue3.0 自定义hooks替代mixin方案，计算公用主体内容高度

 vue3.0 composition api下mixins的替代方式（自定义hooks）：

计算 table列表的响应式高度：

1.新建heightHooks.js

import { ref, onMounted ,nextTick} from 'vue'
export default function () {
  const tableHeight= ref(0)
  onMounted(() => {
    nextTick(()=>{
      let windowHeight = document.documentElement.clientHeight;
      tableHeight.value = windowHeight - 500;
    })
  })
  return {
    tableHeight
  }
}

2.vue页面中引用

setup() {
    const mainHeight  = heightHooks();
    return{
       mainHeight
    }

}

3.高度绑定：

 <el-table :data="tableData" :max-height="mainHeight.tableHeight.value">
</el-table>