jQuery有一个方法特别有用，extend。jQuery自身通过该方法对jQuery进行扩展，在api中用户也可以根据需要对jQuery扩展。

jQuery.extend = jQuery.fn.extend = function() {	var options, name, src, copy, copyIsArray, clone,		target = arguments[0] || {},		i = 1,		length = arguments.length,		deep = false;	// Handle a deep copy situation	if ( typeof target === "boolean" ) {		deep = target;		target = arguments[1] || {};		// skip the boolean and the target		i = 2;	}	// Handle case when target is a string or something (possible in deep copy)	if ( typeof target !== "object" && !jQuery.isFunction(target) ) {		target = {};	}	// extend jQuery itself if only one argument is passed,这里看出该方法默认对jquery扩展。	if ( length === i ) {		target = this;		--i;	}	for ( ; i < length; i++ ) {		// Only deal with non-null/undefined values		if ( (options = arguments[ i ]) != null ) {			// Extend the base object			for ( name in options ) {				src = target[ name ];				copy = options[ name ];				// Prevent never-ending loop				if ( target === copy ) {					continue;				}				// Recurse if we're merging plain objects or arrays				if ( deep && copy && ( jQuery.isPlainObject(copy) || (copyIsArray = jQuery.isArray(copy)) ) ) {					if ( copyIsArray ) {						copyIsArray = false;						clone = src && jQuery.isArray(src) ? src : [];					} else {						clone = src && jQuery.isPlainObject(src) ? src : {};					}					// Never move original objects, clone them					target[ name ] = jQuery.extend( deep, clone, copy );				// Don't bring in undefined values				} else if ( copy !== undefined ) {					target[ name ] = copy;				}			}		}	}	// Return the modified object	return target;  //返回应该算多余，你传递的绑定对象已经modify了。直接使用就好。不改变绑定对象的话还行。};

　　如果需要对jquery类型扩展需要对$.fn原型扩展。

$.extend({	test: function(){		console.log("扩展jQuery");		}});$.extend($.fn,{	test: function(){		console.log("扩展jQuery原型");		}});$.test();$("*").test();