有私人财产ES6类中的方法 [英] Have private properties & methods in ES6 classes

问题描述

我只是试图ES6，并想要重写一部分的代码写在常规javascript到ES6。现在，我试图在ES6类中重写私有属性和方法时卡住了。看起来ES6中的类没有显式地提供任何东西来拥有私有数据或方法。

此外，我查看了此主题： JavaScript ES6类中的私有属性，发现我们可以使用 WeakMap 存储私人数据。这是一种奇怪，但它仍然可以是一个工作。我设法使用它的私人数据。

但是私人方法呢？在ES6类中使用私有方法（或甚至受保护的方法）的推荐方法是什么？

如果任何人都可以向我展示干净方式，使用ES6类和私有方法重写这部分代码，我将非常感激。

谢谢。

这是原来的老的JavaScript代码：

  function Deferred {
 
 //私人数据
 var isPending; 
 var handlers = {
 resolve：[]，
 reject：[]，
 notify：[] 
}; 
 
 //初始化实例
 init（）; 
 
 function init（）{
 isPending = true; 
 this.promise = new Promise（this）; 
} 
 
 //公共方法
 this.resolve = function（value）{
 trigger（'resolve'，value）; 
}; 
 
 this.reject = function（reason）{
 trigger（'reject'，reason）; 
}; 
 
 this.notify = function（value）{
 trigger（'notify'，value）; 
}; 
 
 this.on = function（event，handler）{
 ... 
}; 
 
 //私有方法
函数触发器（事件，参数）{
 ... 
} 
} 
  
 
 
解决方案
 
 
 
似乎ES6中的类没有明确提供任何东西有私人数据或方法。
 
 
正确。  class 语法用于带有原型方法的普通类。如果你想要私有变量，你一直把它们放在构造函数中：
  class Deferred {
 constructor 
 //初始化私有数据
 var isPending = true; 
 var handlers = {
 resolve：[]，
 reject：[]，
 notify：[] 
}; 
 
 //私有方法
函数触发器（事件，参数）{
 ... 
} 
 
 //初始化公共属性
 this.promise = new Promise（this）; 
 
 //并创建特权方法
 this.resolve = trigger.bind（null，'resolve'）; 
 this.reject = trigger.bind（null，'reject'）; 
 this.notify = trigger.bind（null，'notify'）; 
 
 this.on = function（event，handler）{
 ... 
}; 
} 
} 
  
 
I'm just trying out ES6 and want to rewrite a part of code written in regular javascript to ES6. And now, I'm stuck while trying to re-write the private properties and methods in ES6 classes. It seems like classes in ES6 doesn't explicitly provide anything to have private data or methods. 

Also, I checked this thread: Private properties in JavaScript ES6 classes and found out that we could use WeakMap to store private data. Which is sort of weird but still it can be a work around. And I did manage to use it for private data. 

But what about private methods? What is the recommended way to have private methods (or even protected methods) in ES6 classes? 

I would appreciate if anyone can show me a clean way to rewrite this part of code using ES6 class along with the private methods. 

Thanks. 

Here's the plain old javascript code: 
function Deferred() {

    // Private data
    var isPending;
    var handlers = {
        resolve: [],
        reject: [],
        notify: []
    };

    // Initialize the instance
    init();

    function init() {
        isPending = true;
        this.promise = new Promise(this);
    }

    // Public methods
    this.resolve = function(value) {
        trigger('resolve', value);
    };

    this.reject = function(reason) {
        trigger('reject', reason);
    };

    this.notify = function(value) {
        trigger('notify', value);
    };

    this.on = function(event, handler) {
        ...
    };

    // Private method
    function trigger (event, params) {
        ...
    }
}

解决方案

  
It seems like classes in ES6 doesn't explicitly provide anything to have private data or methods.
Correct. The class syntax is for normal classes with prototype methods. If you want private variables, you put them in the constructor as always:
class Deferred {
    constructor() {
        // initialise private data
        var isPending = true;
        var handlers = {
            resolve: [],
            reject: [],
            notify: []
        };

        // Private method
        function trigger(event, params) {
            ...
        }

        // initialise public properties
        this.promise = new Promise(this);

        // and create privileged methods
        this.resolve = trigger.bind(null, 'resolve');
        this.reject = trigger.bind(null, 'reject');
        this.notify = trigger.bind(null, 'notify');

        this.on = function(event, handler) {
            …
        };
    }
}


                        
这篇关于有私人财产ES6类中的方法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！