为什么此内部函数返回未定义? [英] Why does this inner function return undefined?

问题描述

我这样做

function myFunction() {
    var myVar = "I think I am encapsulated";

    function getMyVar() {
        return myVar;
    }
}

var myProperty = myFunction;
myProperty.getMyVar();  // tells me myProperty.getMyVar is not a function.

和

function myFunction() {
    var myVar = "I think I am encapsulated";

    function getMyVar() {
        return myVar;
    }
}

var myProperty = myFunction();
myProperty.getMyVar();   // tells me myProperty is undefined

甚至

function MyFunction() {
    var myVar = "I think I am encapsulated";

    function getMyVar() {
        return myVar;
    }
}

var myProperty = new MyFunction();
myProperty.getMyVar();  // tells me myProperty.getMyVar is not a function.

在所有这三种情况下，我都会遇到问题.我在所有三个部分中均已将该问题作为在线注释中的内容.现在，在有人告诉我只使用闭包之前，我并没有试图了解闭包，而是试图确切地了解内部函数会发生什么.

and in all three cases I get problems. I have included the problem as in line comment in all three sections. Now, before someone tells me to just use a closure, I am not trying to understand closures, I am trying to understand exactly what happens with inner functions.

如果您能在上面解释，我将不胜感激.因为这对我来说很直观.

If you can explain above, I would grateful. Because it is counter intuitive to me.

谢谢

推荐答案

您所做的只是在 myFunction 内部定义一个函数，创建一个闭包...

What you did is just define a function inside myFunction, creating a closure ...

要补救该实现，请将 getMyVar 设置为 实例成员 :

To remedy the implementation, make getMyVar an instance member:

function myFunction() {
    var myVar = "I think I am encapsulated";

    this.getMyVar = function () {
        return myVar;
    }
}

这篇关于为什么此内部函数返回未定义?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！