| jav | Java Source Code |
| Java Source Code Dependency Data |
| java | Java Source Code |
| javajet | Eclipse JET Java Template |
| jba | Jabaco Source Code |
| jbc | Jam STAPL Byte-Code |
| jcc | JX C++ Source Code |
| jci | PSDsoft Express JTAG Chain Information |
| jck | Microsoft Liquid Motion JACK Scene Description |
| jcl | Job Control Language File |
| jcm | JECF Java Commerce Message |
| jco | CelLab Own Code |
| jcs | WebLogic Java Control Source |
| jcx | Java Control Extensions File |
| jdbc | JDBC Configuration |
| jdi | Altera Quartus II JTAG Debugging Information File |
| jfd | JFormDesigner Form Data |
| jfg | JForge Binary Code |
| jfr | Java Flight Recorder Data |
| JRockit Flight Recording File |
| jfs | JRockit Flight Recorder Template |
| jfsl | JForge Specification Language Document |
| jh | JHipster Source Code |
| jhtm | Dynamo Application Server Page |
| ji | Join-Calculus Interface Source Code |
| jic | Altera Quartus II JTAG Indirect Configuration |
| jil | Java in Lisp Source Code |
| jin | Java Servlet Include |
| jio | Join-Calculus JCC Compiled Interface |
| jj | JavaCC Data |
| jjs | Nashorn JJS Script |
| jl | Julia Source Code |
| Sawfish Lisp-based Script Source Code |
| jld | Julia HDF5 Data |
| jlr | Juliar Source Code |
| jlrlib | Juliar Library |
| jlx | JLex Code |
| jmap | CodeWarrior JMAP Data |
| jmdac | Modelio Compiled Module |
| jmf | Java Media Framework Data |
| jmk | JX Makefile |
| jml | Java Modeling Language Specification Data |
| jmo | JMonkey Engine Model |
| jnilib | Java Native Interface Library |
| jomproj | Visual Studio JOOB Object Model Project |
| jop | JOP JOPizer Generated Bytecode |
| jor | Gupta SQLWindows Journal Data |
| joy | CryENGINE Facial Editor Joystick Settings |
| jpage | Eclipse IDE Java Scrapbook Page |
| jpb | J Publish Manager Data |
| jpc | JProbe Coverage Memory Snapshot |
| jpd | Java Process Definition |
| jpf | Java PathFinder Application Property Data |
| jph | JProbe Memory Snapshot |
| jpl | JProbe Settings |
| jpq | JPQ Library |
| jpt | JProbe Threadalyzer Memory Snapshot |
| jpy | JPY Data |
| jq | JQ Script |
| jr | JR Source Code |
| jrag | JastAdd Declarative Aspect |
| jrprint | JasperReports Print Document |
| jrxml | JasperReports Document |
| js | JavaScript |
| JavaScript Style Sheet |
| js1 | Unity Javascript |
| jsa | JRun Server Application |
| jsb | JavaScript Bean |
| JAWS Script Binary File |
| jsbundle | React Native JSBundle |
| jsc | Jeroo Source Code |
| Rhino Compiled Javascript |
| jscript | JScript Source Code |
| Windows Media Player JScript |
| jsd | JAWS Script Documentation File |
| jsdbx | ServiceNow UI Script |
| jsdtscope | Eclipse IDE JavaScript Development Tool Scope Data |
| jsfl | Flash JavaScript |
| jsh | JAWS Script Header |
| Jsh Script |
