Spy
Usage: spy(listener).
Registers a global spy listener that listens to all events that happen in MobX.
It is similar to attaching an observe listener to all observables at once, but also notifies about running (trans/re)actions and computations.
Used for example by the mobx-react-devtools.
Spy listeners always receive one object, which usually has at least a type field. The following events are emitted by default by spy.
| event | fields | nested |
|---|---|---|
| action | name, target (scope), arguments, fn (source function of the action | yes |
| transaction | name, target (scope) | yes |
| scheduled-reaction | object (Reaction instance) | no |
| reaction | object (Reaction instance), fn (source of the reaction) | yes |
| compute | object (ComputedValue instance), target (scope), fn (source) | no |
| error | message | no |
| update (array) | object (the array), index, newValue, oldValue | yes |
| update (map) | object (observable map instance), name, newValue, oldValue | yes |
| update (object) | object (instance), name, newValue, oldValue | yes |
| splice (array) | object (the array), index, added, removed, addedCount, removedCount | yes |
| add (map) | object, name, newValue | yes |
| add (object) | object, name, newValue | yes |
| delete (map) | object, name, oldValue | yes |
| create (boxed observable) | object (ObservableValue instance), newValue | yes |
Note that there are events with the signature { spyReportEnd: true, time? }.
These events might not have a type field, but they are part of an earlier fired event that had spyReportStart: true.
This event indicates the end of an event and this way groups of events with sub-events are created.
This event might report the total execution time as well.
The spy events for observable values are identical to the events passed to observe. See intercept & observe for an extensive overview.
It is possible to emit your own spy events as well. See extras.spyReport, extras.spyReportStart and extras.spyReportEnd