javascript定义类，并实例化的各类之间成员变量不干扰。

var foucs_a = {
	createNew: function(){
		var cls = {
			id:'',
			cur:0,
			_init: function(id) {
				this.id = id;
			},
			next: function() {
				alert(this.cur);
				this.cur++;
			}
		};

		return cls;
	}
};

var fa = foucs_a.createNew();
fa.next();
fa.next();
var fb = foucs_a.createNew();
fb.next();
fb.next();