为什么给的prev传递选择器代码显示出来的结果只有clsaa=“level-3”的2添加上了蓝色的框，而不是每一个2都有边框？

Answer 1

Why does the prev pass selector code show that only the 2 with clsaa="level-3" has a blue frame added, instead of each 2 having a border? -PHP Chinese website Q&A-Why does the prev pass selector code show that only the 2 with clsaa="level-3" has a blue frame added, instead of each 2 having a border? -PHP Chinese website Q&A

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Answer 2

因为做了筛选啊。$('.item-3').prev(':last')这句的意思是：找到类名为item-3的所有紧邻前兄弟节点中的最后一个。所以只有最后一个有蓝色框