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 -~----------~----~----~----~------~----~------~--~---
