grep -Erno 'class[ \t]*=[ \t]*"[^"]+"' *

这也允许有更多的空格，并且应该给你类似的输出：

That will also allow for more whitespace and should give you output similar to:

1:class="foo bar baz"
3:class = "haha"

要查看所有使用的类，可以将输出从上面输出到以下内容：

To see all classes used, you can pipe output from the above into the following:

cut -f2 -d'"' | xargs | sort | uniq