JavaScript中的自定义阵列式getter [英] Custom Array-like getter in JavaScript

问题描述

我有一个简单的ES6类，如下所示：

I have a simple ES6 class, like so:

class Ring extends Array {
    insert (item, index) {
        this.splice(index, 0, item);
        return this;
    }
}

我想让它成为Ring的索引（1，2，3）[3] 返回1，新环（1，2，3）[ - 1] 返回3，依此类推。这是否可能在ES6？如果是这样，我该如何实现？

I want to make it so that the indexing for Ring objects wraps, so that new Ring(1, 2, 3)[3] returns 1, new Ring(1, 2, 3)[-1] returns 3, and so on. Is this possible in ES6? If so, how would I implement it?

我已经阅读了有关代理，这允许一个完全定制的getter，但是我无法弄清楚如何应用代理上课我没有管理这个：

I've read about proxies, which allow a completely customized getter, but I can't figure out how to apply a proxy to a class. I did manage this:

var myRing = new Proxy (Ring.prototype, {
    get: function (target, name) {
        var len = target.length;
        if (/^-?\d+$/.test(name))
            return target[(name % len + len) % len];
        return target[name];
    }
});

myRing 现在是支持的Ring对象包装指数。问题是我每次都要定义这样的Ring对象。有没有办法将此代理应用到类中，以便调用新的Ring（）返回它？

myRing is now a Ring object that supports wrapping indices. The problem is that I'd have to define Ring objects like that every time. Is there a way to apply this proxy to the class such that calling new Ring() returns it?

推荐答案

基本上是

class ProxyRing extends Array {
  constructor(...args) {
    super(...args)

    return new Proxy(this, {
      get: function (target, name) {
          var len = target.length;
          if (typeof name === 'string' && /^-?\d+$/.test(name))
              return target[(name % len + len) % len];
          return target[name];
      }
    });
  }

  insert (item, index) {
      this.splice(index, 0, item);
      return this;
  }
}

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