Javascript runtime environments

Javascript is executed by a javascript engine (ex: v8).
the runtime environment is how you communicate with it.

Generally, this environment is provided by your web browser.
There are also tools like node.js that let you run javascript on the commandline.

Runtime Environments

nodejs	interpreter, cli
spidermonkey	(firefox) includes interpreter, cli

Engines

v8	google chrome's javascript engine
spidermonkey	firefox javascript engine
nitro	safari javascript engine