Index: compile_rules_js_convert.py
==================================================================
--- compile_rules_js_convert.py
+++ compile_rules_js_convert.py
@@ -22,10 +22,11 @@
     sCode = re.sub("\\bnot\\b", "!", sCode)
     sCode = re.sub("(.+) if (.+) else (.+)", "(\\2) ? \\1 : \\3", sCode)
     # boolean
     sCode = sCode.replace("False", "false")
     sCode = sCode.replace("True", "true")
+    sCode = sCode.replace("None", "null")
     sCode = sCode.replace("bool", "Boolean")
     # methods
     sCode = sCode.replace(".__len__()", ".length")
     sCode = sCode.replace(".endswith", ".endsWith")
     sCode = sCode.replace(".find", ".indexOf")