An interesting proposition - although before making a change of this magnitude it would be good to get some performance numbers outlined so that we know how worthwhile it is.
--John On Fri, Aug 14, 2009 at 8:33 PM, lrbabe <lrb...@gmail.com> wrote: > > Hi, > > The principle of .closest( selector ) is that it cycles through the > ancestors of an event target until it finds an element corresponding > to the event target, or hits the root. > To check for an element matching the selectors it uses the .is > ( selector ) function which collects all elements corresponding to the > selector and cycles through them to find if "this" is any of those > elements. > > If my memories about my algorithm lectures are correct, the complexity > of this algorithm is O(n²). Only in the case of a selector of the form > "#id" we have an O(n) complexity. > However, there is another range of selectors that could be checked > with an O(n) algorithm: selectors such as "div", ".class" and > "div.class". In those cases, .is( selector ) is not needed because we > can directly check the ancestor's nodeType and className. > > Reducing the complexity of the .closest() function is particularly > important when using event delegation with the mouseover and mouseout > events: those events fire really often as the user moves his/her > mouse, and the function needs to be used twice: one to check the the > target is in the selector, and one to check that the related target is > in a different ancestor. > > I propose a new implementation of .closest() that is able to detect > those selectors and use them to "fast-check" ancestors. The last > parsed selector is cached to further improve the performances (I'm > just not sure where to cache the parsed selector). > > The code is available as a gist: http://gist.github.com/168158 > and can be tested here: http://www.lrbabe.com/sdoms/closest/ > > Together with the recent addition of the "context" parameter > in .closest(), it makes one of the most efficient event delegation > helper out there. > > Feedback would be much appreciated, > > Regards, > lrbabe > > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "jQuery Development" group. To post to this group, send email to jquery-dev@googlegroups.com To unsubscribe from this group, send email to jquery-dev+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/jquery-dev?hl=en -~----------~----~----~----~------~----~------~--~---
