On http://www.eclipse.org/webtools/jsdt/ it says that the most recent version is 3.4. My Eclipse version is 4.2 Juno.
In Help → Install new software... when I search for it I only get the 1.4 JSDT. I've got the following software sites enabled:
Juno http://download.eclipse.org/releases/juno Enabled
Mylyn for Eclipse Juno http://download.eclipse.org/mylyn/releases/juno Enabled
The Eclipse Project Updates http://download.eclipse.org/eclipse/updates/4.2 Enabled
So how do I install the 3.4 JSDT?