Render header usage of El table

el-table,:render-header

<template>
  <el-table :data="tabledata" style="width: 100%" border>
    <el-table-column prop="oldOrderBy" label=" Sort " :render-header="renderHeader">   
    </el-table-column>
    <el-table-column prop="productName" label=" The product name "></el-table-column>
  </el-table>
</template>
<script>
export default {
  data() {
    return {
      tabledata: [],
      isDragon:true
    };
  },
  created() {
    this.getTableData()
  },
  methods: {
    renderHeader(h, { column }) {
        return h('span', { style: { padding: '0' } }, 
         [
          h('span', { style: { paddingRight: '3px' } }, column.label),
          h('a', {
            style: { color: '#008AE1', fontSize: '12px' },
            on: { click: () => { this.isDragon = false } },
            props: { content: column.label },
          }, ' edit ')
         ]
        )
    },
    getTableData() {
       this.tabledata = [{oldOrderBy:1,productName:' Product 1 '},
                         {oldOrderBy:2,productName:' Product 2 '}];
    },
  }
};
</script>