JavaScript Sandbox

sandbox.js

// Clone an object
// @see https://developer.mozilla.org/en-US/docs/Differential_inheritance_in_JavaScript
Object.prototype.clone = function(){
  // Extract the prototype from the "this" object
  var p = Object.getPrototypeOf(this);

  // Create a new object with p as its prototype
  return Object.create(p);
};

var myGlobalObject = {},
    globalClone = myGlobalObject.clone();

myGlobalObject.myProp = "initial value";

(function(myGlobalObject){
  // sandboxed code
  myGlobalObject.myProp = "new value";
  console.log(myGlobalObject.myProp); // ⇒ "new value"
}(globalClone));

console.log(myGlobalObject.myProp); // ⇒ "initial value"