Checks whether eventTarget accepts listeners for eventName, by adding and immediately removing a no-op listener.
eventTarget
eventName
Some targets (e.g. mock objects, or restricted environments) throw when a listener is added; this lets callers feature-detect instead of failing.
The target to test. undefined is accepted and reported as unsupported.
undefined
The event name to test.
true if a listener could be added, false otherwise.
true
false
Checks whether
eventTargetaccepts listeners foreventName, by adding and immediately removing a no-op listener.Some targets (e.g. mock objects, or restricted environments) throw when a listener is added; this lets callers feature-detect instead of failing.