function addMethod(object, name, f)
{　　
    var old = object[name];　　
    object[name] = function()
    {
        // f.length為函數(shù)定義時(shí)的參數(shù)個(gè)數(shù)
        // arguments.length為函數(shù)調(diào)用時(shí)的參數(shù)個(gè)數(shù)　　　　
        if (f.length === arguments.length)
        {　　
            return f.apply(this, arguments);　　　　
        }
        else if (typeof old === "function")
        {
            return old.apply(this, arguments);　　　　
        }　　
    };
}


// 不傳參數(shù)時(shí)，返回所有name
function find0()
{　　
    return this.names;
}


// 傳一個(gè)參數(shù)時(shí)，返回firstName匹配的name
function find1(firstName)
{　　
    var result = [];　　
    for (var i = 0; i < this.names.length; i++)
    {　　　　
        if (this.names[i].indexOf(firstName) === 0)
        {　　　　　　
            result.push(this.names[i]);　　　　
        }　　
    }　　
    return result;
}


// 傳兩個(gè)參數(shù)時(shí)，返回firstName和lastName都匹配的name
function find2(firstName, lastName)
{　
    var result = [];　　
    for (var i = 0; i < this.names.length; i++)
    {　　　　
        if (this.names[i] === (firstName + " " + lastName))
        {　　　　　　
            result.push(this.names[i]);　　　　
        }　　
    }　　
    return result;
}


var people = {　　
    names: ["Dean Edwards", "Alex Russell", "Dean Tom"]
};


addMethod(people, "find", find0);
addMethod(people, "find", find1);
addMethod(people, "find", find2);


console.log(people.find()); // 輸出["Dean Edwards", "Alex Russell", "Dean Tom"]
console.log(people.find("Dean")); // 輸出["Dean Edwards", "Dean Tom"]
console.log(people.find("Dean", "Edwards")); // 輸出["Dean Edwards"]