adding method for checking presence or absence of attribute

web-world/impl.rkt

@@ -65,6 +65,7 @@
                     view-hide
                     
                     view-attr
+                    view-has-attr?
                     update-view-attr
                     remove-view-attr
 

web-world/js-impl.js

@@ -216,6 +216,10 @@
         return $(this.cursor.node[0]).attr(name);
     };
 
+    MockView.prototype.hasAttr = function(name) {        
+        return $(this.cursor.node[0]).attr(name) !== undefined;
+    };
+
 
     MockView.prototype.updateAttr = function(name, value) {
         return this.act(
@@ -1923,6 +1927,14 @@
             return view.getAttr(name);
         });
 
+    EXPORTS['view-has-attr?'] = makePrimitiveProcedure(
+        'view-has-attr?',
+        2,
+        function(MACHINE) {
+            var view = checkMockViewOnElement(MACHINE, 'view-has-attr?', 0);
+            var name = checkSymbolOrString(MACHINE, 'view-has-attr?', 1).toString();
+            return view.hasAttr(name);
+        });
 
     EXPORTS['update-view-attr'] = makePrimitiveProcedure(
         'update-view-attr',

web-world/racket-impl.rkt

@@ -18,7 +18,7 @@
          view-backward
          
          view-text update-view-text
-         view-attr update-view-attr remove-view-attr
+         view-attr view-has-attr? update-view-attr remove-view-attr
          view-css update-view-css
          view-id
 
@@ -148,6 +148,9 @@
 (define (view-attr v attr-name)
   (error 'view-attr "Please run in JavaScript context."))
 
+(define (view-has-attr? v attr-name)
+  (error 'view-has-attr? "Please run in JavaScript context."))
+
 (define (update-view-attr v attr-name value)
   (error 'update-view-attr "Please run in JavaScript context."))