ES6类 - 更新静态属性 [英] ES6 Classes - Updating Static Properties

问题描述

我试图找出将静态（或类）属性设置为ES6类的替代方法，然后在创建类的新实例后更改它。

I am trying to figure out alternative ways to set a static (or class) property an ES6 Class and then change it after new instances of the class are created.

例如，假设我有一个名为 Geo 的类，我需要一个名为<$ c的静态属性$ c>所有，它将为我提供 Geo 类的所有实例的数组。

For example, lets say I have a class called Geo, and I need a static property called all that will give me the array of all instances of the Geo class.

此版本有效：

class Geo {
  constructor(name){
    this.name = name;
    Geo.all.push(this);
  }
}

Geo.all = [];

ruby = new Geo("Ruby");
rocks = new Geo("Rocks");
console.log(Geo.all.length); // => 2

我宁愿不设置类定义的属性OUTSIDE。我尝试了一些东西，但似乎无法在类中创建一个静态属性，我可以从构造函数更新。

I would prefer to not set the property OUTSIDE of the class definition though. I've tried a few things but can't seem to create a static property within the class that I can update from the constructor.

我还应该提一下，我需要能够在浏览器（Chrome）中执行此操作而不使用Babel或类似功能。

I should also mention I need to be able to do this in the browser (Chrome) without use of Babel or similar.

以下是我尝试过的一些事情的例子：

Here are examples of some things I've tried:

class Geo {
  constructor(name){
    this.name = name;
    Geo.all.push(this);
  }
  static get all() {
    return [];
  }
}

ruby = new Geo("Ruby");
rocks = new Geo("Rocks");
console.log(Geo.all.length); // => 0 

另一个

class Geo {
  constructor(name){
    this.name = name;
    Geo.all.push(this);
  }

  static all = [];
}

ruby = new Geo("Ruby");
rocks = new Geo("Rocks");
console.log(Geo.all.length); // => error unexpected "="

推荐答案

没有这样的事情< ES6 中的code> static all = [] 。 实例和 static 字段是目前阶段3的提案，可以通过转换器使用，例如巴贝尔。 TypeScript中已经存在可能以某种方式与这些提案不兼容的实现，但 static all = [] 在 TS 和 ES.Next 。

There's no such thing as static all = [] in ES6. Class instance and static fields are currently stage 3 proposals which can be used via a transpiler, e.g. Babel. There's already existing implementation in TypeScript that may be incompatible with these proposals in some way, yet static all = [] is valid in TS and ES.Next.

Geo.all = [];

是在ES6中执行此操作的有效和可取的方法。替代方案是getter / setter对 - 或者只有get-only属性的getter：

is valid and preferable way to do this in ES6. The alternative is getter/setter pair - or only a getter for read-only property:

class Geo {
  static get all() {
    if (!this._all)
      this._all = [];

    return this._all;
  }

  constructor() { ... }
}

静态属性中的跟踪实例通常不能被认为是一个好的模式，并且会导致无法控制的内存消耗和泄漏（正如评论中提到的那样）。

Tracking instances in static property can't generally be considered a good pattern and will lead to uncontrollable memory consumption and leaks (as it was mentioned in comments).

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