exploring scope isolation (sandboxing) in JS

1.js

sandbox (JSON) { // explicitly list everything to import from the outer scope

   var foobar = "baz"; // scoped to this sandbox
   baz = "foobar"; // still scoped to this sandbox, not auto-global.

   console.log(JSON); // available!

   console.log(window); // not available because not imported

   console.log(this); // undefined
}

console.log(baz); // undefined

2.js

var foobar = sandbox() {

   baz = function() { // NOTE: no `var` statement necessary
      console.log("awesome");
   };

   return {
      baz: baz
   };
};

console.log(foobar.baz); // defined
console.log(baz); // undefined

2better.js

var foobar = sandbox() {

   baz = function() { // NOTE: no `var` statement necessary
      console.log("awesome");
   };

   export baz; // borrowing this syntax from ES6 modules
};

console.log(foobar.baz); // defined
console.log(baz); // undefined

Another reason I'm declaring scope symbol-imports in the sandbox declaration is that I think it should be the containing code's job to declare what scope symbols the isolation can access, not the contained code itself. I really hate the import semantics in ES6 modules for that reason (in addition to the conflation with module-loading).

I'm pretty sure we'll end up using module loaders on the web and we'll only use import in the server. I'm not sure they're specified (modules are still WIP), but I wouldn't be surprised if there can be anonymous modules.

Regarding your code... I think it's a bad bad idea to drop the var keyword. Strict mode does it right by throwing an error.