Why is the Temp.prototype on the MDN Object.create

问题:

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

Temp.prototype = null;

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

The 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;
    };
  })();
}

回答1:

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.

回答2:

I think this is just clean, Temp.prototype is kind of static, since it is set before new Temp() it is nice to clean it after.