Realizzato dalla risposta Blender. Destinato a quelli del mio livello.
Sebbene non si tratti di un vero e proprio termine, la seguente è una ripartizione del significato previsto di surrogate-prototipo-swapping mediante un commento più completo del codice originale underscore.js.
// A function which will be used as a constructor function in order
// to add a prototype to a new object. There is nothing special about
// this function, except how it will be used.
var Ctor = function(){};
// Create a shortcut to Object.create if it exists. Otherwise
// nativeCreate will be undefined
var nativeCreate = Object.create;
// An internal function that will use or act as a polyfill for
// Object.create, with some type checking built in.
var baseCreate = function(prototype) {
// Check if the object passed to baseCreate is actually an object.
// Otherwise simply return an object (from an object literal),
// because there is not a valid object to inherit from.
if (!_.isObject(prototype)) return {};
// If Object.create is implemented then return the value
// returned by Object.create when the prototype parameter is
// passed into it. If Object.create has already been
// implemented there is no need to recreate it. Just return
// its return value.
if (nativeCreate) return nativeCreate(prototype);
// If Object.create is not defined then Ctor comes into play.
// The object passed to baseCreate is assigned to the prototype
// of Ctor. This means when Ctor is called prototype will be
// the prototype assigned to this (the keyword this).
Ctor.prototype = prototype;
// Because Ctor is called with the new keyword this (the
// keyword this) is returned returned by Ctor. Thus, the
// variable 'result' is assigned an object with a prototype
// equal to baseCreate's parameter 'prototype'.
var result = new Ctor;
// Then to reset things Ctor.prototype is set to null.
Ctor.prototype = null;
// The newly created object, whose prototype is the object
// passed to baseCreate is returned.
return result;
};
Stavo leggendo il codice di Underscore e ho incontrato lo stesso dubbio. –