elementUI 下拉框实现隐藏时触发相关事件

el-select 下拉框隐藏时触发相关事件 =>@visible-change
设置额外的class，=> popper-class

	@visible-change="changeValue1($event)"

	changeValue1: function(callback, vc) {
				//只有回调参数为true时才触发 ctx.getAreaListDataSearch(vc,1)这个函数;
				if (callback === true) {
					document.getElementsByClassName("quhua")[0].style.zIndex = "-1";
				} else {
					document.getElementsByClassName("quhua")[0].style.zIndex = "1200";
				}
			},