Another possibility is Harbour To Java, then compile Java with the Google Web Toolkit (GWT).
So, (according GWT docs):
Java technologies offer a productive development plaform, and with GWT, they can instantly become the basis of your AJAX development platform as well. Here are some of the benefits of developing with GWT:
* You can use all of your favorite Java development tools (Eclipse, IntelliJ, JProfiler, JUnit) for AJAX development.
* Static type checking in the Java language boosts productivity while reducing errors.
* Code prompting/completion is widely available.
* Automated Java refactoring is pretty snazzy these days.
* Java-based OO designs are easier to communicate and understand, thus making your AJAX code base more comprehensible with less documentation."