这个CSS选择器是什么？

Question

I'm having a custom styled checkboxes with image insead of the dom element. It's using this selector. What this selector do? +em is bugging me big time :)

input[type='checkbox']:checked+em::before

Please help.

Answer 1

The + is an adjacent sibling combinator . So that selector selects the em element immediately following a checked checkbox. This is as distinct from the general sibling combinator , ~ , which would match any following sibling of the input even if not right next to it.

Answer 2

创建一个伪元素，该元素是em标记的第一个子元素，该元素位于具有选中的属性类型复选框的输入元素之前。