As of 2017, Javamap and Zoom Map no longer exist. The feature has been removed. The raster map you see on every trip page is now just a static .png file, (like a .jpg file), and always works in any environment.
The old Javamap and Zoommap require your browser to have a Java Interpreter plug-in. This can be downloaded for free from http://java.com. However certain old operating systems are no longer supported such as Windows XP.
the best thing is to search google for your operating system, your browser and "Java"
Windows 7, Internet Explorer and Java
Windows 7 and Java
Windows 10 and Java
Macbook Pro and Java
In the past, I've written various notes on this, but there are now so many operating systems - browser combinations.
See Javamap Troubleshooting.