Espruino interrupt handles or TestSet-TestReset-synchronized javascript equivalents for semaphore-thread handling

Watch events get queued up, with the times they're taken at recorded (e.time, e.lastTime, e.state) - I think you could compare those to the current time to detect how long it's been between the interrupt being triggered, and your function running. The queue is 128 events long on Espruino 1v3.