如何在不外部返回内部的情况下访问内部函数
[英]How to access function inside function without outer returning inner one
问题描述
I have got a function 'alpha', and there is another function 'beta' inside it. 
我有一个函数“ alpha”，里面还有另一个函数“ beta”。 If I don't return beta in alpha, then how to access beta. 如果我不返回alpha测试版，那么如何访问beta。 Is there anyway of doing this? 反正有这样做吗？ (Like, I can access alpha writing window.alpha(), as in global context alpha becomes a property of window object, then how to access beta as property, via window dom tree)? （就像，我可以访问alpha编写window.alpha（），因为在全局上下文中alpha成为窗口对象的属性，然后如何通过窗口dom树将beta作为属性访问）？
<html> <head></head> <body> <script> function alpha() { console.log("hi"); function beta() { console.log("hello"); } } alpha(); //works window.alpha(); //works beta(); //it is directly not accessible. How to access it if alpha does not return it </script> </body> </html>
alpha() is in Window Dom but why not beta? alpha（）在Window Dom中，但为什么不是beta？ (Even not inside alpha) （即使不在alpha内）
4 个解决方案
解决方案1
3 已采纳 2018-04-12 07:37:51
Normally you can not do this thing either you can prefer these option but in these you have to call alpha once in order to get beta 通常，您不能执行此操作，或者您更喜欢这些选项，但是在这些操作中，您必须调用一次alpha才能获得beta
//first option //第一个选项
(function alpha() {
console.log("hi");
function beta() {
console.log("hello");
}
window.beta = beta;
})()
//second option //第二个选项
Use this to create beta as property in alpha 使用this来创建beta作为alpha属性
function alpha() {
this.beta = function() {
console.log("hello");
}
}
let alphaObject = new alpha();
alphaObject.beta();
解决方案2
2 2018-04-12 07:32:07
If you don't want to return beta , you could return this and define beta as this.beta : 如果您不想返回beta ，则可以返回this并将beta定义为this.beta ：
To access beta() , you simply need to call alpha().beta() . 要访问beta() ，您只需要调用alpha().beta() 。
function alpha() { console.log("hi"); this.beta = () => { console.log("hello"); } return this; } alpha().beta();
解决方案3
2 2018-04-12 07:49:11
The beta() method is private to function alpha. beta（）方法专用于功能alpha。 The way Javascript scoping works prevents you from directly accessing the inner functions . Javascript范围定义的工作方式可防止您直接访问内部函数。 Create it as a property of alpha by using this.beta 使用this.beta其创建为alpha的属性
解决方案4
1 2018-04-12 07:33:14
Declare beta as a member of alpha using this : 使用this beta声明为alpha成员：
function alpha() { console.log("hi"); this.beta = function() { console.log("hello"); } } let a = new alpha(); a.beta();
You current implementation prevents JavaScript from accessing beta from outside of alpha . 您当前的实现阻止JavaScript从alpha之外访问beta 。 Read more about private functions in JavaScript. 阅读有关JavaScript中私有函数的更多信息。
Using this you can actually attach such methods to the instances of the function alpha . 使用this方法，您实际上可以将这些方法附加到函数alpha的实例。 That's what I've done in this solution. 这就是我在此解决方案中所做的。
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