给数组对象添加contains方法：是否包某一对象
????????//数组是否存在某一对象Array.prototype.contains = function(obj) {this.obj = obj;var that = this;function isExist() {for (var i = 0, j = that.length; i < j; i++) {if (that[i] == obj) {return true;}}return false;}return isExist();}