diff --git a/js/js-impl.js b/js/js-impl.js
index a76ceaf..636d40e 100644
--- a/js/js-impl.js
+++ b/js/js-impl.js
@@ -1,68 +1,135 @@
-var VOID = plt.baselib.constants.VOID_VALUE;
-var makePrimitiveProcedure = plt.baselib.functions.makePrimitiveProcedure;
+/*jslint devel: true, browser: false, unparam: true, sub: true, windows: false, vars: true, white: true, maxerr: 50, indent: 4 */
 
-EXPORTS['alert'] =
-    makePrimitiveProcedure(
-        'alert',
-        1,
-        function(MACHINE) {
-            var elt = MACHINE.e[MACHINE.e.length - 1];
-            alert(String(elt));
-            return VOID;
-        });
+/*global $,plt,EXPORTS,document,window*/
+(function() {
+    "use strict";
+
+    var VOID = plt.baselib.constants.VOID_VALUE;
+    var makePrimitiveProcedure = plt.baselib.functions.makePrimitiveProcedure;
+    var makeCheckArgumentType = plt.baselib.check.makeCheckArgumentType;
+    var checkSymbolOrString = plt.baselib.check.checkSymbolOrString;
+    var checkAny = makeCheckArgumentType(function(x) { return true; },
+                                         "any");
+
+    EXPORTS['alert'] =
+        makePrimitiveProcedure(
+            'alert',
+            1,
+            function(MACHINE) {
+                var elt = MACHINE.e[MACHINE.e.length - 1];
+                alert(String(elt));
+                return VOID;
+            });
 
 
-EXPORTS['body'] = $(document.body);
+    EXPORTS['body'] = $(document.body);
 
-EXPORTS['$'] =
-    makePrimitiveProcedure(
-        '$',
-        1,
-        function(MACHINE) {
-            var obj = MACHINE.e[MACHINE.e.length - 1];
-            return $(obj);
-        });
+    EXPORTS['$'] =
+        makePrimitiveProcedure(
+            '$',
+            1,
+            function(MACHINE) {
+                var obj = MACHINE.e[MACHINE.e.length - 1];
+                return $(obj);
+            });
 
-EXPORTS['call-method'] = 
-    makePrimitiveProcedure(
-        'call-method',
-        plt.baselib.arity.makeArityAtLeast(2),
-        function(MACHINE) {
-            var obj = MACHINE.e[MACHINE.e.length - 1];
-            var methodName = MACHINE.e[MACHINE.e.length - 2];
-            var args = [];
-            for (var i = 0; i < MACHINE.a - 2; i++) {
-                args.push(MACHINE.e[MACHINE.e.length -1 - 2 - i]);
-            }
-            var result = obj[methodName].apply(obj, args);
-            return result;
-        });
+    EXPORTS['call-method'] = 
+        makePrimitiveProcedure(
+            'call-method',
+            plt.baselib.arity.makeArityAtLeast(2),
+            function(MACHINE) {
+                var obj = MACHINE.e[MACHINE.e.length - 1];
+                var methodName = MACHINE.e[MACHINE.e.length - 2];
+                var args = [], i;
+                for (i = 0; i < MACHINE.a - 2; i = i+1) {
+                    args.push(MACHINE.e[MACHINE.e.length -1 - 2 - i]);
+                }
+                var result = obj[methodName].apply(obj, args);
+                return result;
+            });
+
+
+    EXPORTS['window'] = window;
+
+
+    EXPORTS['get-attr'] =
+        makePrimitiveProcedure(
+            'get-attr',
+            plt.baselib.arity.makeArityAtLeast(2),
+            function(MACHINE) {
+                var obj = checkAny(MACHINE, 'get-attr', 0), attr, i;
+                for (i = 1; i < MACHINE.a; i = i + 1) {
+                    attr = checkSymbolOrString(MACHINE, 'get-attr', i).toString();
+                    obj = obj[attr];
+                }
+                return obj;
+            });
+
+
+    EXPORTS['set-attr!'] =
+        makePrimitiveProcedure(
+            'set-attr!',
+            3,
+            function(MACHINE) {
+                var obj = checkAny(MACHINE, 'set-attr!', 0);
+                var attr = checkSymbolOrString(MACHINE, 'set-attr!', 1).toString();
+                var val = checkAny(MACHINE, 'set-attr!', 2);
+                obj[attr] = val;
+                return VOID;
+            });
+
+    EXPORTS['js-string?'] = 
+        makePrimitiveProcedure(
+            'js-string?',
+            1,
+            function(MACHINE) {
+                return typeof(checkAny(MACHINE, 'js-string?', 0)) === 'string';
+            });
+
+    EXPORTS['string->js-string'] =
+        makePrimitiveProcedure(
+            'string->js-string',
+            1,
+            function(MACHINE) {
+                return checkString(MACHINE, 'string->js-string', 0).toString();
+            });
+
+    EXPORTS['js-string->string'] =
+        makePrimitiveProcedure(
+            'js-string->string',
+            1,
+            function(MACHINE) {
+                return checkJsString(MACHINE, 'string->js-string', 0);
+            });
 
 
 
 
-// Javascript-specific extensions.  A small experiment.
-EXPORTS['viewport-width'] = 
-    makePrimitiveProcedure(
-        'viewport-width',
-        0,
-        function(MACHINE) {
-            return $(window).width();
-        });
-
-EXPORTS['viewport-height'] = 
-    makePrimitiveProcedure(
-        'viewport-height',
-        0,
-        function(MACHINE) {
-            return $(window).height();
-        });
 
 
-EXPORTS['in-javascript-context?'] =
-    makePrimitiveProcedure(
-        'in-javascript-context?',
-        0,
-        function(MACHINE) {
-            return true;
-        });
+    // Javascript-specific extensions.  A small experiment.
+    EXPORTS['viewport-width'] = 
+        makePrimitiveProcedure(
+            'viewport-width',
+            0,
+            function(MACHINE) {
+                return $(window).width();
+            });
+
+    EXPORTS['viewport-height'] = 
+        makePrimitiveProcedure(
+            'viewport-height',
+            0,
+            function(MACHINE) {
+                return $(window).height();
+            });
+
+
+    EXPORTS['in-javascript-context?'] =
+        makePrimitiveProcedure(
+            'in-javascript-context?',
+            0,
+            function(MACHINE) {
+                return true;
+            });
+}());
\ No newline at end of file
diff --git a/js/main.rkt b/js/main.rkt
index f07bd97..f4c77e5 100644
--- a/js/main.rkt
+++ b/js/main.rkt
@@ -8,6 +8,13 @@
                     call-method
                     $
 
+                    get-attr
+                    set-attr!
+
+                    js-string?
+                    string->js-string
+                    js-string->string
+                    
                     viewport-width
                     viewport-height
                     in-javascript-context?
diff --git a/js/racket-impl.rkt b/js/racket-impl.rkt
index 86a26e1..4787435 100644
--- a/js/racket-impl.rkt
+++ b/js/racket-impl.rkt
@@ -18,6 +18,23 @@
   'not-done-yet)
 
 
+(define (get-attr object attr . other-attrs)
+  (error 'get-attr "Not available outside JavaScript context"))
+
+
+(define (set-attr! obj attr value)
+  (error 'set-attr! "Not available outside JavaScript context"))
+
+
+
+(define (js-string? x)
+  (error 'js-string? "Not available outside JavaScript context"))
+(define (string->js-string x)
+  (error 'string->js-string "Not available outside JavaScript context"))
+(define (js-string->string x)
+  (error 'js-string->string "Not available outside JavaScript context"))
+
+
 
 
 ;; in-javascript-context: -> boolean
diff --git a/storage/storage.rkt b/storage/storage.rkt
new file mode 100644
index 0000000..5c9f73e
--- /dev/null
+++ b/storage/storage.rkt
@@ -0,0 +1,3 @@
+#lang s-exp "../lang/base.rkt"
+
+(require "../js.rkt")
\ No newline at end of file