diff --git a/README b/README
index 3d7947a..e9b65d9 100644
--- a/README
+++ b/README
@@ -27,7 +27,10 @@ Example:
         page5.mediaBox.getUpperRight_y() / 2
     )
     output.addPage(page5)
-
+    
+    # add some Javascript to launch the print window on opening this PDF
+    output.addJS("this.print({bUI:true,bSilent:false,bShrinkToFit:true});")
+    
     # print how many pages input1 has:
     print "document1.pdf has %s pages." % input1.getNumPages())
 
diff --git a/pyPdf/pdf.py b/pyPdf/pdf.py
index bf60d01..74e3b3a 100644
--- a/pyPdf/pdf.py
+++ b/pyPdf/pdf.py
@@ -86,18 +86,43 @@ def __init__(self):
                 })
         self._info = self._addObject(info)
 
+    
+        # js object
+        js = DictionaryObject()
+        js.update({
+            NameObject("/Type"): NameObject("/Action"),
+            NameObject("/S"): NameObject("/Javascript"),
+            NameObject("/JS"): NameObject(u"(app.alert({cMsg: 'Hello from PDF JavaScript', cTitle: 'Testing PDF JavaScript', nIcon: 3});)")
+        })
+
         # root object
         root = DictionaryObject()
         root.update({
             NameObject("/Type"): NameObject("/Catalog"),
             NameObject("/Pages"): self._pages,
+            # NameObject("/OpenAction"): self._addObject(js),
             })
-        self._root = self._addObject(root)
+        # self._root = self._addObject(root)
+        self._root = None
+        self.root = root
 
     def _addObject(self, obj):
         self._objects.append(obj)
         return IndirectObject(len(self._objects), 0, self)
 
+    def addJS(self, str):
+        js = DictionaryObject()
+        js.update({
+            NameObject("/Type"): NameObject("/Action"),
+            NameObject("/S"): NameObject("/JavaScript"),
+            # NameObject("/JS"): NameObject(u"(app.alert({cMsg: 'Hello from PDF JavaScript', cTitle: 'Testing PDF JavaScript', nIcon: 3});)")
+            NameObject("/JS"): NameObject("(" + str + ")"),
+        })
+
+        self.root.update( {
+            NameObject("/OpenAction"): self._addObject(js)
+            } )
+
     def getObject(self, ido):
         if ido.pdf != self:
             raise ValueError("pdf must be self")
@@ -240,6 +265,9 @@ def encrypt(self, user_pwd, owner_pwd = None, use_128bit = True):
     def write(self, stream):
         import struct
 
+        if(not self._root):
+            self._root = self._addObject(self.root)
+
         externalReferenceMap = {}
 
         # PDF objects sometimes have circular references to their /Page objects