An instance of JSContext represents a JavaScript execution environment. All

 JavaScript execution takes place within a context.

 JSContext is also used to manage the life-cycle of objects within the

 JavaScript virtual machine. Every instance of JSValue is associated with a

 JSContext via a strong reference. The JSValue will keep the JSContext it

 references alive so long as the JSValue remains alive. When all of the JSValues

 that reference a particular JSContext have been deallocated the JSContext

 will be deallocated unless it has been previously retained.