Js中如何获取当月的一号和最后一天

      let date = new Date()
      // 获取服务器时区
      let offsetTime = date.getTimezoneOffset() * 60 * 1000
      // 根据当天获取本月第一天和最后一天
      let firstDay = new Date(date.getFullYear(), date.getMonth(), 1)
      let lastDay = new Date(date.getFullYear(), date.getMonth() + 1, 0)
      
      // 转换为ISO格式，可以赋值给组件
      firstDay.setTime(firstDay.getTime() - offsetTime)
      lastDay.setTime(lastDay.getTime() - offsetTime)
      this.dateRange = [firstDay.toJSON(), lastDay.toJSON()]