给el-table的表头某列添加自定义el-dropdown，点击无效的问题

slot的方式：

                      <el-table-column prop="policyNo" label="号码" :align="columnAlign"><template slot="header"><el-dropdown trigger="hover" @command="handleCommand"><span style="font-size:12px;font-weight:100">号码<i class="el-icon-arrow-down el-icon--right" /></span><el-dropdown-menu slot="dropdown"><el-dropdown-item command="a">选中全部</el-dropdown-item><el-dropdown-item command="b">取消选中全部</el-dropdown-item></el-dropdown-menu></el-dropdown></template></el-table-column>

render-header的方式：

<el-table-column prop="policyNo" :align="columnAlign" :render-header="renderEmotionValue" />

renderEmotionValue(creatElement, { column, $index }) {return (<el-dropdown onCommand={this.handleCommand }><span style="font-size:12px;font-weight:100">号码<i class='el-icon-arrow-down el-icon--right'></i></span><el-dropdown-menu slot='dropdown'><el-dropdown-item command='a' >选中全部</el-dropdown-item><el-dropdown-item command='b'>取消选中全部</el-dropdown-item></el-dropdown-menu></el-dropdown>)}

注意：

两种方式的触发事件的写法不一样：
@command=“handleCommand” 和 onCommand={this.handleCommand }