GWT-Jep is virtually compatible with the Jep 3.4 release, apart from the following changes:
- Only the ConfigurableParser is supported and not the JavaCC based StandardParser.
 
- There is no support for Serialization, the SerializableExpression class has been removed, 
and some serialization specific methods have been removed.
 
- Javascript has no integer datatype so any calculations which would use integers are performed as doubles.
 
- Google compatibility classes com.google.gwt.i18n.client.NumberFormat, used.
 
- Simple re-implementations of Reader, StringReader and BufferedReader are provided in com.singularsys.jep.compatibility. 
   Note Reader has a single 
public String readLine() which must be implemented by any subclasses. 
- Simple re-implementations of Observer and Observable are provided in com.singularsys.jep.compatibility.
  
- Simple re-implementations of Pattern and Matcher are provided in com.singularsys.jep.compatibility
   these only implement the Matcher.lookingAt() method and not Matcher.find(). These use com.google.gwt.regexp.shared.RegExp class.
 
- Some change in the format of message in Exceptions.
 
- New line character assumed to be \n.
 
- The com.singularsys.jep.misc.functions.IsType is not supported.