从myModal中删除tabindex="-1"似乎可以完成任务:小提琴

Removing tabindex="-1" from myModal seems to do the job: Fiddle

问题是tabindex，因为如果将其设置为-1，则将无法访问该元素. 更多信息此处，以及此

The problem is tabindex, because if you set it to -1, you won't be able to access that element. More info here, and in this question.