JavaScript isn't Java and is Off Topic here.

ECMAScript is the standard. Microsoft IE implements this as JScript and
provides their own extensions. Other browsers implmenent it in their own
way (Mozilla implements it as "JavaScript" and provides its own
extensions). Although there is havoc in the differences, there are a lot
of features that are common. Try searching on google for "javascript
cross browser help" or look for a javascript/ecmascript newsgroup.