切换到弹框: switch_to_alert()
① alert.accept() 确认弹框
driver.switch_to_alert().accept()
② alert.dismiss() 取消弹框
driver.switch_to_alert().dismiss()
③ alert.text 获取弹框文本
④ alert.send_keys() 输入字符
driver.switch_to_alert().send_keys()