To select a child node in jQuery one can use children() but also find().
For example:
$(this).children(\'.foo\');
gives the same result
This jsPerf test suggests that find() is faster. I created a more thorough test, and it still looks as though find() outperforms children().
Update: As per tvanfosson's comment, I created another test case with 16 levels of nesting. find() is only slower when finding all possible divs, but find() still outperforms children() when selecting the first level of divs.
children() begins to outperform find() when there are over 100 levels of nesting and around 4000+ divs for find() to traverse. It's a rudimentary test case, but I still think that find() is faster than children() in most cases.
I stepped through the jQuery code in Chrome Developer Tools and noticed that children() internally makes calls to sibling(), filter(), and goes through a few more regexes than find() does.
find() and children() fulfill different needs, but in the cases where find() and children() would output the same result, I would recommend using find().