JavaScript OSA, (originally JavaScript for OSA, abbreviated as JSOSA), is a freeware inter-process communication scripting language for the Macintosh computer.
JavaScript OSA uses the "core language" of the Mozilla implementation of the JavaScript programming language, (see SpiderMonkey). The language is used as an alternative to the AppleScript language. Its use is unrelated to web browser-based scripting. It can be seen as having a similar function to Microsoft's JScript .NET language on Windows machines, although there is no interoperability between the two languages' system-level scripting.