为什么MDN Object.create polyfill上的Temp.prototype设置为null？ [英] Why is the Temp.prototype on the MDN Object.create polyfill set to null?

问题描述

为什么Object.create的MDN polyfill具有以下行：

Why does the MDN polyfill for Object.create have the following line:

Temp.prototype = null;

我们是否避免维护对原型参数的引用，从而加快垃圾收集速度？

Is it so that we avoid maintaining a reference to the prototype argument enabling faster garbage collection?

polyfill：

if (typeof Object.create != 'function') {
  Object.create = (function() {
    var Temp = function() {};
    return function (prototype) {
      if (arguments.length > 1) {
        throw Error('Second argument not supported');
      }
      if (typeof prototype != 'object') {
        throw TypeError('Argument must be an object');
      }
      Temp.prototype = prototype;
      var result = new Temp();
      Temp.prototype = null;
      return result;
    };
  })();
}

推荐答案

是的，完全正确。这个polyfill确实将 Temp 函数永久保存在内存中（因此它的平均速度更快，不需要为每次调用创建一个函数），并在其上重置 .prototype 是必要的，这样它就不会泄漏。

Yes, exactly. This polyfill does hold the Temp function forever in memory (so that its faster on average, not needing to create a function for every invocation of create), and resetting the .prototype on it is necessary so that it does not leak.

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