核心jQuery核心函数jQuery(expr,[context])jQuery(html,[ownerDoc])jQuery(elements)jQuery(callback)jQuery对象访问each(callback)size()lengthselectorcontextget()get(index)index(subject)数据缓存data(name,[value])removeData(name)queue(name,[cb|queue])dequeue(name)插件机制jQuery.fn.extend(object)jQuery.extend(obje