原型实例

function Fruits() {}
        Fruits.prototype = {
            color: 'red',
            say: function(num1, num2) {
                return 'i am ' + this.color + num1 + ' and ' + num2;
            }
        };
        var apple = new Fruits();
        alert(apple.say(1,2));
        banana = {
            color:'yellow'
        };

        alert(Fruits.prototype.say.call(banana, [1, 2]));
//        alert(Fruits.prototype.say.apply(banana, [1, 2]));

会有出错，call的【1，2】被解析为字符串1，2放入num1，而num2为undefined;