jQuery .on 效率

Question

第一个 .on 函数比第二个更有效吗？

$( "div.container" ).on( "click", "p", function(){
});

$( "body" ).on( "click", "p", function(){
});

问候

Answer 1

来自 jQuery 文档本身关于 jQuery: .on() :

jQuery can process simple selectors of the form tag#id.class very quickly when they are used to filter delegated events. So, "#myForm", "a.external", and "button" are all fast selectors. Delegated events that use more complex selectors, particularly hierarchical ones, can be several times slower--although they are still fast enough for most applications. Hierarchical selectors can often be avoided simply by attaching the handler to a more appropriate point in the document. For example, instead of $( "body" ).on( "click", "#commentForm .addNew", addComment ) use $( "#commentForm" ).on( "click", ".addNew", addComment ).