jQuery.contains() : Check to see if a DOM element is a descendant of another DOM element.
仅仅支持文档元素
Note: The first argument must be a DOM element, not a jQuery object or plain JavaScript object.
jQuery.each() : A generic iterator function, which can be used to seamlessly iterate over both objects and arrays. Arrays and array-like objects with a length property (such as a function's arguments object) are iterated by numeric index, from 0 to length-1. Other objects are iterated via their named properties.
jQuery.extend() : Merge the contents of two or more objects together into the first object.
第一个参数为ture时，执行深拷贝，target为第二个参数
jQuery.globalEval() : Execute some JavaScript code globally.
jQuery.grep() : Finds the elements of an array which satisfy a filter function. The original array is not affected.
类似于es5 的filter
jQuery.inArray() : Search for a specified value within an array and return its index (or -1 if not found).
jQuery.isArray() : returns a Boolean indicating whether the object is a JavaScript array (not an array-like object, such as a jQuery object)
jQuery.isEmptyObject(): Check to see if an object is empty (contains no enumerable properties).
jQuery.isPlainObject() : Check to see if an object is a plain object (created using "{}" or "new Object").
jQuery.makeArray() : Convert an array-like object into a true JavaScript array.
jQuery.map() : Translate all items in an array or object to new array of items.
类似于es5 map方法 ，区别1）返回null时，值不被包含在结果中2）映射函数返回的如果是数组，则该数组被添加到结果数组中，而不是数组本身中
jQuery.merge() : Merge the contents of two arrays together into the first array.
jQuery.parseJSON() : Takes a well-formed JSON string and returns the resulting JavaScript value.
jQuery.proxy() : Takes a function and returns a new one that will always have a particular context.
类似于es5的bind,但它没有像bind()方法那样实现参数的部分应用。
jQuery.trim() : Remove the whitespace from the beginning and end of a string.
If these whitespace characters occur in the middle of the string, they are preserved