模块显示原型模式-私有变量

Question

I am using the module reveal prototype pattern ( https://weblogs.asp.net/dwahlin/techniques-strategies-and-patterns-for-structuring-javascript-code-revealing-prototype-pattern ), and am having trouble accessing my this variable in my prototype functions. I have this code:

myapp.ConfirmationWindow = function (temptype) {
    this._type = temptype;
};

myapp.ConfirmationWindow.prototype = function () {
    this._showConfirmationWindow = function (message) {
        var a = this._type; //valid
        return _showWindow("hello");    
    }

    this._showWindow = function (message) {
        var a= this._type; //invalid
    }
    return {
        showConfirmationWindow: _showConfirmationWindow
    };
}();

I am able to access this._type in _showConfirmationWindow(), but am not able to access this._type in _showWindow. The different is that the prototype is setting _showConfirmationWindow() as public and _showWindow as private, but why doesn't _showWindow get access to this._type. Why is this the case.

One solution I found is to pass this as an extra parameter in _showWindow

Answer 1

_showWindow don't have a this reference to your instance because it's not part of ConfirmationWindow prototype because by returning only showConfirmationWindow , it never gets assigned to the prototype. You could use call to invoke your private functions like:

_showWindow.call(this, "hello")

Or adding a second argument to _showWindow like and pass the this reference when you invoke it:

_showWindow(message, self)

But i would prefer the first one.