一、监听route

场景：监听浏览器地址栏分页参数的变化

// 注意 newPageNum和 oldPageNum是 string类型
'$route.query.pageNum'(newPageNum, oldPageNum) {if (newPageNum !== oldPageNum && newPageNum !== this.pageNum.toString()) {this.handleCurrentChange(parseInt(newPageNum) || 1);}
},'$route.query.pageSize'(newPageSize, oldPageSize) {if (newPageSize !== oldPageSize && newPageSize !== this.pageSize.toString()) {this.handleSizeChange(parseInt(newPageSize) || 20);}
}

二、监听state

场景：监听菜单栏的折叠与展开的状态

watch: {'$store.state.isCollapse'(newVal, oldV) {this.isCollapse = newVal}
},