Disallow empty selectors.


  a, , b {}
/** ↑ 
 * An empty selector */

Empty selectors (by themselves or within a selector list) invalidate a rule. This rule splits the selector list on ,. Any part that has zero length or containing only whitespace is deemed empty.

空选择器(它们本身或在选择器列表内)会使一个规则失效。该规则使用 , 把选择器列表分开。任何长度为 0 的 或只包含空白的部分被认为是空的。



The following patterns are considered warnings:


, .a, .b {}
.a, .b,  {}
.a, , .b {}

The following patterns are not considered warnings:


a {}
a, b {}
a.foo {}