offEvent(obj, eventName, callback)

Unregister an event handler from the object obj that had previously been registered with onEvent. The function passed as callback will no longer be called when the event named eventName is dispatched on obj.

var obj = new DefineMap({ foo: "bar" });
var handler = function(ev, newVal, oldVal) {
    console.log("foo is now", newVal, ", was", oldVal);
};

canReflect.onEvent(obj, "foo", handler);
canReflect.offEvent(obj, "foo", handler);

canEvent.dispatch.call(obj, "foo", ["baz", "quux"]);  // -> nothing is logged