A simple implementation of a javascript parser in javascript. (Used as a REPL implementation)

sandbox.js

var Sandbox;

Sandbox = (function() {
  function Sandbox() {}

  Sandbox.prototype.alert = function(message) {
    return console.log(message);
  };

  Sandbox.exec = function(code, sandbox, module) {
    var func;
    if (sandbox == null) {
      sandbox = new Sandbox();
    }
    if (module == null) {
      module = {};
    }
    func = new Function("module", "with(this){return(function(module,global,window){\"use strict\";return eval(\"" + code + "\");})(module,this,this)}");
    return func.call(sandbox, module);
  };

  return Sandbox;

}).call(this);

sandbox.spec.coffee

describe "Sandbox", ->

  beforeEach ->
    @sandbox = new Sandbox()
    @module = createSpyObj "module", [ "module_test_fn" ]

  describe "#exec", ->
    it "should provide access to context based globals", ->
      spyOn @sandbox, "alert"
      Sandbox.exec "alert('foobar');", @sandbox, @module
      expect( @sandbox.alert ).toHaveBeenCalled()
    it "should provide access to module", ->
      Sandbox.exec "module.module_test_fn();", @sandbox, @module
      expect( @module.module_test_fn ).toHaveBeenCalled()
    it "should not leak variables to global scope", ->
      try Sandbox.exec "variable_should_not_be_global = 'variable_should_not_be_global';", @sandbox, @module
      try Sandbox.exec "this.variable_should_not_be_global = 'variable_should_not_be_global';", @sandbox, @module
      try Sandbox.exec "global.variable_should_not_be_global = 'variable_should_not_be_global';", @sandbox, @module
      try Sandbox.exec "window.variable_should_not_be_global = 'variable_should_not_be_global';", @sandbox, @module
      try Sandbox.exec "var variable_should_not_be_global = 'variable_should_not_be_global';", @sandbox, @module
      expect( global.variable_should_not_be_global ).not.toBeDefined()
    it "should return output from code", ->
      expect( Sandbox.exec("'return_value'", @sandbox, @module) ).toBe "return_value"