Improving jQuery.filter performances for simple selectors would benefit .is(), .hasClass(), .closest() and .live()

[lrbabe]

Currently .is() and .hasClass() underlying algorithm has an O(n) complexity while .closest() and .live() complexity is O(n²). However, for simple selectors of the form "div", ".class" or "div.class" the complexity could respectively be O and O(n) by directly checking the nodes without querying the DOM.

The attached patch adds a dozen lines of code to jQuery.filter() to enable this behavior and has a very limited impact on performance for other selectors.

See related post on google groups for additional details and performance numbers: ​http://groups.google.com/group/jquery-dev/browse_thread/thread/99dc2e890e423bd7

[lrbabe]

Fix a bug in the previous proposed patch

[dmethvin]

Sorry about the long delay here. Could you re-review the proposed patch to see if it still applies?

[trac-o-bot]

Because we get so many tickets, we often need to return them to the initial reporter for more information. If that person does not reply within 14 days, the ticket will automatically be closed, and that has happened in this case. If you still are interested in pursuing this issue, feel free to add a comment with the requested information and we will be happy to reopen the ticket if it is still valid. Thanks!