创建命名空间

function createNamespace(name){

	var domains = name.split('.');

	var cur_domain = window;

	for(var i=0,len=domains.length;i<len;i++){

		var domain = domains[i];

		if(typeof cur_domain[domain] == 'undefined'){

			cur_domain[domain] = {};

		}

		cur_domain = cur_domain[domain]

	}

	return cur_domain;

}