有时还要看边界：空数据怎么办，网络慢怎么办，用户重复点击怎么办。
Sometimes you also need to consider edge cases: what to do with empty data, what to do with slow network, what to do with repeated user clicks.
Sometimes you also need to consider edge cases: what to do with empty data, what to do with slow network, what to do with repeated user clicks.