Selecting class instances

Class instances in JavaScript are created using the new keyword. In SYNG, (of) selects such instantiations, which has a form similar to that of (call) that we've already seen.

(of) has the following signature:

(of [class] [args])

Selecting by class

The first argument to (of) accepts any valid JavaScript expression, not only class declarations or expressions, since technically any object that has a prototype with a constructor function can be instantiated using new.

For example, to select all instances of a Promise:

(of Promise)

Which would match new Promise().

Selecting by arguments

The second argument to (of) behaves exactly like the one for (call), so you can refer to it for more information. For example, to select a Promise that was created with only a resolution handler:

(of Promise
    (:and (arg 1)
          (:not (arg 2))))