diff --git a/dom/bindings/Codegen.py b/dom/bindings/Codegen.py
index fff76939e634..7938e10cca52 100644
--- a/dom/bindings/Codegen.py
+++ b/dom/bindings/Codegen.py
@@ -10,7 +10,7 @@ import re
 import string
 
 from WebIDL import BuiltinTypes, IDLBuiltinType, IDLNullValue, IDLSequenceType, IDLType
-from Configuration import NoSuchDescriptorError, getTypesFromDescriptor, getTypesFromDictionary, getTypesFromCallback
+from Configuration import NoSuchDescriptorError, getTypesFromDescriptor, getTypesFromDictionary, getTypesFromCallback, Descriptor
 
 AUTOGENERATED_WARNING_COMMENT = \
     "/* THIS FILE IS AUTOGENERATED - DO NOT EDIT */\n\n"
@@ -476,8 +476,9 @@ class CGHeaders(CGWrapper):
     Generates the appropriate include statements.
     """
     def __init__(self, descriptors, dictionaries, callbacks,
-                 callbackDescriptors, declareIncludes, defineIncludes, child,
-                 config=None):
+                 callbackDescriptors,
+                 declareIncludes, defineIncludes, child,
+                 config=None, anyJSImplemented=False):
         """
         Builds a set of includes to cover |descriptors|.
 
@@ -586,7 +587,7 @@ class CGHeaders(CGWrapper):
             # And we need BindingUtils.h so we can wrap "this" objects
             declareIncludes.add("mozilla/dom/BindingUtils.h")
 
-        if len(callbackDescriptors) != 0:
+        if len(callbackDescriptors) != 0 or anyJSImplemented:
             # We need CallbackInterface to serve as our parent class
             declareIncludes.add("mozilla/dom/CallbackInterface.h")
             # And we need BindingUtils.h so we can wrap "this" objects
@@ -7075,7 +7076,8 @@ class CGBindingRoot(CGThing):
                                               workers=True)
         callbackDescriptors = config.getDescriptors(webIDLFile=webIDLFile,
                                                     isCallback=True)
-
+        jsImplemented = config.getDescriptors(webIDLFile=webIDLFile,
+                                              isJSImplemented=True)
         forwardDeclares = [CGClassForwardDeclare('XPCWrappedNativeScope')]
 
         descriptorsForForwardDeclaration = list(descriptors)
@@ -7229,6 +7231,11 @@ class CGBindingRoot(CGThing):
         # Do codegen for all the callback interfaces
         cgthings.extend([CGCallbackInterface(x) for x in callbackDescriptors])
 
+        # Do codegen for JS implemented classes
+        for x in jsImplemented:
+            cgthings.append(CGCallbackInterface(x))
+            cgthings.append(CGJSImplClass(x))
+
         # And make sure we have the right number of newlines at the end
         curr = CGWrapper(CGList(cgthings, "\n\n"), post="\n\n")
 
@@ -7267,7 +7274,8 @@ class CGBindingRoot(CGThing):
                           'nsDOMQS.h'
                           ],
                          curr,
-                         config)
+                         config,
+                         anyJSImplemented = len(jsImplemented) != 0)
 
         # Add include guards.
         curr = CGIncludeGuard(prefix, curr)
@@ -8059,6 +8067,8 @@ class CGCallback(CGClass):
         name = idlObject.identifier.name
         if descriptorProvider.workers:
             name += "Workers"
+        if isinstance(descriptorProvider, Descriptor) and descriptorProvider.interface.isJSImplemented():
+            name = jsImplName(name)
         # For our public methods that needThisHandling we want most of the
         # same args and the same return type as what CallbackMember
         # generates.  So we want to take advantage of all its
diff --git a/dom/bindings/Configuration.py b/dom/bindings/Configuration.py
index 8e3e6888f4d1..49aedea0eaea 100644
--- a/dom/bindings/Configuration.py
+++ b/dom/bindings/Configuration.py
@@ -113,6 +113,8 @@ class Configuration:
                 getter = lambda x: x.interface.isCallback()
             elif key == 'isExternal':
                 getter = lambda x: x.interface.isExternal()
+            elif key == 'isJSImplemented':
+                getter = lambda x: x.interface.isJSImplemented()
             else:
                 getter = lambda x: getattr(x, key)
             curr = filter(lambda x: getter(x) == val, curr)
@@ -213,7 +215,7 @@ class Descriptor(DescriptorProvider):
         # Do something sane for JSObject
         if self.nativeType == "JSObject":
             headerDefault = "jsapi.h"
-        elif self.interface.isCallback():
+        elif self.interface.isCallback() or self.interface.isJSImplemented():
             # A copy of CGHeaders.getDeclarationFilename; we can't
             # import it here, sadly.
             # Use our local version of the header, not the exported one, so that
diff --git a/dom/bindings/parser/WebIDL.py b/dom/bindings/parser/WebIDL.py
index 8d5ebd05a1d6..f334ad34cc16 100644
--- a/dom/bindings/parser/WebIDL.py
+++ b/dom/bindings/parser/WebIDL.py
@@ -779,7 +779,7 @@ class IDLInterface(IDLObjectWithScope):
         return self._callback
 
     def isSingleOperationInterface(self):
-        assert self.isCallback()
+        assert self.isCallback() or self.isJSImplemented()
         return (
             # Not inheriting from another interface
             not self.parent and