Expression builder

[joe.camilleri]

I'm looking for some java script code that I can use in an HTML page to
allow a user to build a logical expression. The user should be able to
select from a list of variables and operators such as +-() etc. Also,
the user should be able to easily modify the expression without having
to type in values manually.

If anyone knows of any open source or vendor products that allow this
please let me know. Note the environment I am working in does not allow
the use of java applets

Thanks