javascript - Dynamically calling an object's private functions

Question

I can't seem to dynamically call the private method add from a public function. It seems that this only accesses the public scope which is why I'm not able to call add. Is there a way to do this?

function test()
{
    var actionCollection = [];

    function add( int1, int2 )
    {
        return int1 + int2;
    }

    this.callFunc = function( testMethodFunction, methodArguments )
    {
        this[testMethodFunction].apply(null, methodArguments);//Method 'add' not found.
    }
}

var t = new test();

alert( t.callFunc( 'add', [1,2] ) );

Plus I'm not exactly sure what null is supposed to do considering you can also use this in the apply argument. Could I also have some clarification on what the first argument of apply is supposed to do? Since this is also related to my original question. Thanks in advance for any help!

Answer 1

这是因为add()不是 的属性Test，它只是Test()闭包中的局部变量。

这是一个示例代码：

function Test()
{
    var _priv = {
        add: function ( int1, int2 )
        {
            console.log(int1, int2);
            return int1 + int2;
        }
    };

    this.callFunc = function( testMethodFunction, methodArguments )
    {
        console.log(_priv);
        return _priv[testMethodFunction].apply(null, methodArguments);
    }
}

var t = new Test();

console.log(t);

console.log( t.callFunc( 'add', [1,2] ) );

给你的一些提示：

• 对类结构使用大写（Test而不是test）

• 使用log()您的优势来检查对象

Answer 2

add不是 的一部分this。因此你不能使用this[testMethodFunction]. 如果你想保持隐私，那么你可以使用这样的东西：

function test() {
    var actionCollection = [];

    var private_methods = {
        add: function( int1, int2 ) {
            return int1 + int2;
        }
    }

    this.callFunc = function( testMethodFunction, methodArguments )
    {
        // note the change here!
        return private_methods[testMethodFunction].apply(null, methodArguments);
    }
}

var t = new test();

alert( t.callFunc( 'add', [1,2] ) );