jQuery中live()变更

开始的时候在jQuery.1.7.1中使用了.live()觉得很好用，特别是在绑定事件之后再加入的元素的事件绑定上很方便(第一次live之后以后添加的元素就不需要绑定啦)

后来jQuery更新到1.9.1，页面中的.live报错:"has no method live", 后来查了文档才知道在新版本中做了修改。

//jQuery.1.8.3：
$("#liveID").live("click",function(){alert("live click");});

//jQuery.1.9.1：
$(document).on("click","#liveID",function(){alert("live click");});

As of jQuery 1.7, the .live() method is deprecated. Use .on() to attach event handlers. Users of older versions of jQuery should use .delegate() in preference to .live().

This method provides a means to attach delegated event handlers to the document element of a page, which simplifies the use of event handlers when content is dynamically added to a page. See the discussion of direct versus delegated events in the.on() method for more information.

改进后的使用建议：

$(selector).live(events, data, handler); // jQuery 1.3+
$(document).delegate(selector, events, data, handler); // jQuery 1.4.3+
$(document).on(events, selector, data, handler); // jQuery 1.7+

$("a.offsite").live("click", function(){ alert("Goodbye!"); }); // jQuery 1.3+
$(document).delegate("a.offsite", "click", function(){ alert("Goodbye!"); }); // jQuery 1.4.3+
$(document).on("click", "a.offsite", function(){ alert("Goodbye!"); }); // jQuery 1.7+