dax/vm.js

A Lisp for JavaScript

(function () {
  var vm = {};
  var contextifiedSandboxes = [];

  function createIFrame() {
    var iframe = document.createElement('iframe');
    iframe.style.display = 'none';
    return iframe;
  }

  function createIFrameWithContext(sandbox) {
    var iframe = createIFrame();
    var key;
    document.body.appendChild(iframe);
    if (sandbox) {
      for (key in sandbox) {
        if (sandbox.hasOwnProperty(key)) {
          iframe.contentWindow[key] = sandbox[key];
        }
      }
      contextifiedSandboxes.push(sandbox);
    }
    return iframe;
  }

  function runCodeInNewContext(code, sandbox) {
    var iframe = createIFrameWithContext(sandbox);
    var result = iframe.contentWindow.eval(code);
    document.body.removeChild(iframe);
    return result;
  }

  function runCodeInContext(code, context) {
    if (!context) {
      throw new Error('Context cannot be undefined');
    }
    return context.eval(code);
  }

  function Script(code) {
    this.code = code;
  }

  Script.prototype.runInContext = function (context) {
    return runCodeInContext(this.code, context);
  };

  Script.prototype.runInNewContext = function (sandbox) {
    return runCodeInNewContext(this.code, sandbox);
  };

  Script.prototype.runInThisContext = function () {
    return runCodeInContext(this.code, window);
  };

  vm.Script = Script;

  vm.createContext = function (sandbox) {
    return createIFrameWithContext(sandbox).contentWindow;
  };

  vm.isContext = function (sandbox) {
    return contextifiedSandboxes.indexOf(sandbox) !== -1;
  };

  vm.runInContext = function (code, context) {
    return runCodeInContext(code, context);
  };

  vm.runInDebugContext = function () {
    throw new Error('vm.runInDebugContext(code) does not work in browsers');
  };

  vm.runInNewContext = function (code, sandbox) {
    return runCodeInNewContext(code, sandbox);
  };

  vm.runInThisContext = function (code) {
    return runCodeInContext(code, window);
  };
  
  vm.createScript = function (code) {
    return new vm.Script(code);
  };

  window.vm = window.vm || vm;
})();