With improvements in V8, using separate emit functions is no longer
necessary and can instead be replaced by the spread operator.
improvement confidence p.value
events/ee-emit.js n=2000000 2.98 % 0.09852489
events/ee-emit-2-args.js n=2000000 4.19 % *** 0.0001914216
events/ee-emit-6-args.js n=2000000 61.69 % *** 6.611964e-35
events/ee-emit-diff-args.js n=2000000 -0.36 % 0.305069
events/ee-once.js n=20000000 6.42 % *** 1.27831e-06
PR-URL: https://github.com/nodejs/node/pull/16869
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: Bryan English <bryan@bryanenglish.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Timothy Gu <timothygu99@gmail.com>
Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>
Reviewed-By: Benedikt Meurer <benedikt.meurer@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Brian White <mscdex@mscdex.net>
The initials of expected in TypeError[ERR_INVALID_ARG_TYPE]
are inconsistent. This change is to unify them.
PR-URL: https://github.com/nodejs/node/pull/16401
Fixes: https://github.com/nodejs/node/issues/16383
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Due to changes in V8 in 6.0 & 6.1, it's no longer necessary to copy
arguments to avoid deopt. Just call .apply with arguments. Retains
fast cases for 0-3 arguments.
events/ee-once-4-args.js n=20000000 11.58 % *** 1.310379e-05
PR-URL: https://github.com/nodejs/node/pull/16212
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
With recent changes in V8, it is now as performant or faster to use
spread parameter within EventEmitter.prototype.emit, especially
in cases where looping over arguments is required.
events/ee-emit.js n=2000000 4.40 % *** 1.505543e-06
events/ee-emit-1-arg.js n=2000000 2.16 % *** 2.434584e-10
events/ee-emit-2-args.js n=2000000 1.05 % ** 0.001764852
events/ee-emit-3-args.js n=2000000 2.18 % *** 3.234954e-08
events/ee-emit-6-args.js n=2000000 17.17 % *** 1.298702e-103
events/ee-emit-10-args.js n=2000000 17.14 % *** 1.144958e-97
This has a knock-on effect for modules that use events extensively,
such as http2:
http2/headers.js nheaders=0 n=1000 2.10 % *** 6.792106e-11
PR-URL: https://github.com/nodejs/node/pull/16212
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Each conditional branch in EventEmitter.prototype.listeners assigns
its return value to a variable ret which is returned at the end.
Instead just return from within each branch. This is both clearer
and more performant.
events/ee-listeners.js n=5000000 3.65 % *** 3.359171e-10
PR-URL: https://github.com/nodejs/node/pull/16212
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Previously, console had to be compiled in case it was not available
but this is no longer necessary - remove it.
PR-URL: https://github.com/nodejs/node/pull/16212
Refs: https://github.com/nodejs/node/pull/15111
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Replace truthy/falsey checks of _events and _events[type] with
comparisons to undefined for better performance:
events/ee-add-remove.js n=250000 5.30 % *** 4.260028e-07
events/ee-emit.js n=2000000 4.18 % *** 1.026649e-05
This has a knock-on effect on modules that use lots of events, e.g.:
http2/headers.js nheaders=0 n=1000 2.60 % *** 0.000298338
PR-URL: https://github.com/nodejs/node/pull/16212
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
lib/url.js and lib/events.js are using the same spliceOne function.
This change is to move it into the internal/util for avoiding duplicate
code.
PR-URL: https://github.com/nodejs/node/pull/16221
Reviewed-By: Timothy Gu <timothygu99@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
In preparation for stricter indentation linting and to increase code
clarity, update indentation for ternaries in lib.
PR-URL: https://github.com/nodejs/node/pull/14247
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: James M Snell <jasnell@gmail.com>
Commit 8d386ed7e1 stopped the
Event Emitter implementation from storing arrays containing a
single listener. This change left a section of code in
removeListener() as unreachable. This commit removes the
unreachable code.
Refs: https://github.com/nodejs/node/pull/12043
PR-URL: https://github.com/nodejs/node/pull/12501
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Use the remaining listener directly if the array of listeners has only
one element after running `EventEmitter.prototype.removeListener()`.
Advantages:
- Better memory usage and better performance if no new listeners are
added for the same event.
Disadvantages:
- A new array must be created if new listeners are added for the same
event.
PR-URL: https://github.com/nodejs/node/pull/12043
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>
Reviewed-By: Ron Korving <ron@ronkorving.nl>
Update error message that's thrown when no error listeners are attached
to an emitter.
PR-URL: https://github.com/nodejs/node/pull/10387
Reviewed-By: Sam Roberts <vieuxtech@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Italo A. Casas <me@italoacasas.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
PR-URL: https://github.com/nodejs/node/pull/11938
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Yuta Hiroto <hello@about-hiroppy.com>
Reviewed-By: Brian White <mscdex@mscdex.net>
Fix a TypeError when emitting an 'error' argument with a non-object
argument (like a string) when domains are active.
Fixes: https://github.com/nodejs/help/issues/501
PR-URL: https://github.com/nodejs/node/pull/11438
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
This commit makes sure EventEmitter.emit() doesn't get deoptimized by
V8. The deopt happens when accessing out of bound indexes of the
`arguments` object.
This issue has been raised here: #10323 and this specific case might
become a more serious performance issue in upcoming V8 releases.
PR-URL: https://github.com/nodejs/node/pull/10568
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
array.shift() seems to be faster than arrayClone() when the item
to remove is at the front (at least with V8 5.4).
PR-URL: https://github.com/nodejs/node/pull/10572
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Optimize arrayClone by copying forward.
It's slightly faster (and more readable) to copy array elements
in forward direction. This way it also avoids the ToBoolean and
the postfix count operation.
PR-URL: https://github.com/nodejs/node/pull/10571
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>
This commit takes advantage of the performance improvements V8 has
made to function.bind() in V8 5.4 and uses it to avoid constant
recompilation/reoptimization of the wrapper closure used in once().
This change results in ~27% performance increase for once().
PR-URL: https://github.com/nodejs/node/pull/10445
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Teddy Katz <teddy.katz@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
This commit removes two truthy checks for object properties that
are immediately followed by a strict equality check. The other
item in the comparison is guaranteed to be a function by this
point in the code, so the truthy check is redundant.
PR-URL: https://github.com/nodejs/node/pull/9330
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Allows Symbol to be converted to String so it can be included in the
error.
Fixes: https://github.com/nodejs/node/issues/9003
PR-URL: https://github.com/nodejs/node/pull/9021
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>
This makes the famous `EventEmitter memory leak` warnings occurring
when the listener count for a given event exceeds a specified number
more programatically accessible, by giving them properties referring
to the event emitter instance and the event itself.
This can be useful for debugging the origins of such a warning when
the stack itself doesn’t reveal enough information about the event
emitter instance itself, e.g. when manual inspection of the
already-registered listeners is expected to be useful.
PR-URL: https://github.com/nodejs/node/pull/8298
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Jeremiah Senkpiel <Fishrock123@rocketmail.com>
When removing a `once` listener, the listener being passed to
the `removeListener` callback is the wrapper. This unwraps the
listener so that `removeListener` is passed the actual listener.
PR-URL: https://github.com/nodejs/node/pull/6394
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
A handful of modules (including readable-streams) make
inappropriate use of the internal _events property. One
such use is to prepend an event listener to the front
of the array of listeners.
This adds EE.prototype.prependListener() and
EE.prototype.prependOnceListener() methods to add handlers
to the *front* of the listener array.
Doc update and test case is included.
Fixes: https://github.com/nodejs/node/issues/1817
PR-URL: https://github.com/nodejs/node/pull/6032
Reviewed-By: Сковорода Никита Андреевич <chalkerx@gmail.com>
Reviewed-By: Brian White <mscdex@mscdex.net>
Use `Reflect.ownKeys()` instead of `Object.keys()` and
`Object.getOwnPropertySymbols()`.
PR-URL: https://github.com/nodejs/node/pull/5822
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
This commit safely allows event names that are named the same as
properties that are ordinarily inherited from Object.prototype such
as __proto__.
Fixes: https://github.com/nodejs/node/issues/728
PR-URL: https://github.com/nodejs/node/pull/6092
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
In several places throughout the code we write directly to stderr
to report warnings (deprecation, possible eventemitter memory leak).
The current design of simply dumping the text to stderr is less
than ideal. This PR introduces a new "process warnings" mechanism
that emits 'warning' events on the global process object. These are
invoked with a `warning` argument whose value is an Error object.
By default, these warnings will be printed to stderr. This can be
suppressed using the `--no-warnings` and `--no-deprecation` command
line flags. For warnings, the 'warning' event will still be emitted
by the process, allowing applications to handle the warnings in custom
ways. The existing `--no-deprecation` flag will continue to supress
all deprecation output generated by the core lib.
The `--trace-warnings` command line flag will tell Node.js to print
the full stack trace of warnings as part of the default handling.
The existing `--no-deprecation`, `--throw-deprecation` and
`--trace-deprecation` flags continue to work as they currently do,
but the exact output of the warning message is modified to occur
on process.nextTick().
The stack trace for the warnings and deprecations preserve and point
to the correct call site.
A new `process.emitWarning()` API is provided to permit userland
to emit warnings and deprecations using the same consistent
mechanism.
Test cases and documentation are included.
PR-URL: https://github.com/nodejs/node/pull/4782
Reviewed-By: Rod Vagg <rod@vagg.org>
Reviewed-By: Wyatt Preul <wpreul@gmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Per https://github.com/nodejs/node/issues/1817, there are many modules
that currently abuse the private `_events` property on EventEmitter.
One of the ways it is used is to determine if a particular event is
being listened for. This adds a simple `eventNames()` method that
returns an array of the events with currently registered listeners.
PR-URL: https://github.com/nodejs/node/pull/5617
Reviewed-By: Brian White <mscdex@mscdex.net>
Reviewed-By: Сковорода Никита Андреевич <chalkerx@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
This commit fixes some error messages that are not consistent with
some general rules which most of the error messages follow.
PR-URL: https://github.com/nodejs/node/pull/3374
Reviewed-By: Roman Reiss <me@silverwind.io>
Now parts of our public and public-ish APIs fall back to old-style
listenerCount() if the emitter does not have a listenerCount function.
Fixes: https://github.com/nodejs/node/issues/2655
Refs: 8f58fb92ff
PR-URL: https://github.com/nodejs/node/pull/2661
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
As per the discussion in #734, this patch deprecates the usage of
`EventEmitter.listenerCount` static function in the docs, and introduces
the `listenerCount` function in the prototype of `EventEmitter` itself.
PR-URL: https://github.com/nodejs/node/pull/2349
Reviewed-By: Trevor Norris <trev.norris@gmail.com>
Reviewed-By: Brian White <mscdex@mscdex.net>
Previously, in the event of an unhandled error event, if the error is a
not an actual Error, then a default error is thrown. Now, the argument
is appended to the error message and added as the `context` property
of the error.
PR-URL: https://github.com/iojs/io.js/pull/1654
Reviewed-By: Rod Vagg <rod@vagg.org>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Not including `new` adds a useless frame and removes a potentially
useful frame.
PR-URL: https://github.com/iojs/io.js/pull/1246
Reviewed-By: Petka Antonov <petka_antonov@hotmail.com>
Reviewed-By: Roman Reiss <me@silverwind.io>
Reviewed-By: Brendan Ashworth <brendan.ashworth@me.com>
This both switches to a single algorithm for array cloning and also
speeds up (by ~100% in the ee-listeners-many benchmark) the
"many elements" case that was previously handled by
`array.slice()`.
PR-URL: https://github.com/iojs/io.js/pull/1050
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Julian Duque <julianduquej@gmail.com>
These optimizations result in >2x speedup in the ee-add-remove
benchmark:
* Don't mutate array.length when removing the last listener for
an event
* Don't bother checking max listeners if listeners isn't an array
* Don't call delete when removing the last event in _events, just
re-assign a new object instead
PR-URL: https://github.com/iojs/io.js/pull/785
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Evan Lucas <evanlucas@me.com>
This keeps in line with how things are done for the fast path
and *might* even provide a *slight* performance increase.
PR-URL: https://github.com/iojs/io.js/pull/785
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Evan Lucas <evanlucas@me.com>
Cache events and listeners objects where possible and loop over
Object.keys() instead of using for..in. These changes alone give
~60-65% improvement in the ee-add-remove benchmark.
The changes to EventEmitter.listenerCount() gives ~14%
improvement and changes to emitter.listeners() gives
significant improvements for <50 listeners
(~195% improvement for 10 listeners).
The changes to emitter.emit() gives 3x speedup for the fast
cases with multiple handlers and a minor speedup for the slow
case with multiple handlers.
The swapping out of the util.is* type checking functions with inline
checks gives another ~5-10% improvement.
PR-URL: https://github.com/iojs/io.js/pull/601
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Evan Lucas <evanlucas@me.com>
Many of the util.is*() methods used to check data types
simply compare against a single value or the result of
typeof. This commit replaces calls to these methods with
equivalent checks. This commit does not touch calls to the
more complex methods (isRegExp(), isDate(), etc.).
Fixes: https://github.com/iojs/io.js/issues/607
PR-URL: https://github.com/iojs/io.js/pull/647
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
This commit replaces a number of var statements throughout
the lib code with const statements.
PR-URL: https://github.com/iojs/io.js/pull/541
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Commit 2931348 added EventEmitter#getMaxListeners() but introduced a
regression when people abuse EventEmitter.prototype.on.call() to call
EventEmitter#on() on a non-EE object. Add a workaround for that.
Fixes: https://github.com/iojs/io.js/issues/523
PR-URL: https://github.com/iojs/io.js/pull/527
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
The copyright and license notice is already in the LICENSE file. There
is no justifiable reason to also require that it be included in every
file, since the individual files are not individually distributed except
as part of the entire package.
Replace the call to Array#splice() with a faster open-coded version
that creates less garbage.
Add a new benchmark to prove it. With the change applied, it scores
a whopping 40% higher.
PR-URL: https://github.com/iojs/io.js/pull/185
Reviewed-By: Chris Dickinson <christopher.s.dickinson@gmail.com>
Turn on strict mode for the files in the lib/ directory. It helps
catch bugs and can have a positive effect on performance.
PR-URL: https://github.com/node-forward/node/pull/64
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Fedor Indutny <fedor@indutny.com>
Before this commit the EventEmitter methods were anonymous functions.
V8 tries to infer names for anonymous functions based on the execution
context but it frequently gets it wrong and when that happens, the
stack trace is usually confusing and unhelpful. This commit names all
methods so V8 can fall back to the method.name property.
The above gotcha applies to all anonymous functions but is exacerbated
for EventEmitter methods because those are invoked with a plenitude of
different receivers.
Signed-off-by: Trevor Norris <trev.norris@gmail.com>
Without this check it is possible to have the _events object shared
amongst instances.
Fixes #7157
Signed-off-by: Trevor Norris <trev.norris@gmail.com>
This is a slightly modified revert of bc39bdd.
Getting domains to use AsyncListeners became too much of a challenge
with many edge cases. While this is still a goal, it will have to be
deferred for now until more test coverage can be provided.
After landing 6ed861d it is no longer possible to reliably monkey-patch
the EventEmitter constructor. However there's valid use cases for that,
and makes for easier debugging. Therefore, move the guts of the
constructor to a separate function which is monkey-patchable.
Closes #6693
Check that `listeners` is actually an array before trying to manipulate it
because it won't be if no regular event listeners have been registered yet
but there are 'removeListener' event listeners.
Emitting an event within a `EventEmitter#once` callback of the same
event name will cause subsequent `EventEmitter#once` listeners of the
same name to be called multiple times.
var emitter = new EventEmitter();
emitter.once('e', function() {
emitter.emit('e');
console.log(1);
});
emitter.once('e', function() {
console.log(2);
});
emitter.emit('e');
// Output
// 2
// 1
// 2
Fix the issue, by calling the listener method only if it was not
already called.
The domain module has been switched over to use the domain module API as
much as currently possible. There are still some hooks in the
EventEmitter, but hopefully we can remove those in the future.
This change is 100% backwards compatible.
This change will make using `EventEmitter` slightly simpler / nicer and
adheres to the best practice set forth by substack.
```js
var EventEmitter = require("events")
var emitter = new EventEmitter()
```
The only difference is that we now have to set `EventEmitter` as a
property of `EventEmitter` for backwards compatibility like we do with
[`Stream`][1]
We have also set the `usingDomains` property on the `EventEmitter`
constructor itself because that aligns with it's current usage of
`require("events").usingDomains = true`
There are other internals that would benefit from this change as well
like `StringDecoder`
Before this commit, events were set to undefined rather than deleted
from the EventEmitter's backing dictionary for performance reasons:
`delete obj.key` causes a transition of the dictionary's hidden class
and that can be costly.
Unfortunately, that introduces a memory leak when many events are added
and then removed again. The strings containing the event names are never
reclaimed by the garbage collector because they remain part of the
dictionary.
That's why this commit makes EventEmitter delete events again. This
effectively reverts commit 0397223.
Fixes #5970.
so `ee.emit('error')` doesn't throw when domains are active
create an empty error only when handled by a domain
test for when no error is provided to an error event
Strict checking for typeof types broke backwards compatibility for other
libraries. This reverts those checks.
The subclass test has been changed to ensure all operations can be
performed on the inherited EE before instantiation. Including the
ability to set event names with numbers.
By making sure the _events is always an object there is one less check
that needs to be performed by emit.
Use undefined instead of null. typeof checks are a lot faster than
isArray.
There are a few places where the this._events check cannot be removed
because it is possible for the user to call those methods after using
utils.extend to create their own EventEmitter, but before it has
actually been instantiated.
Unnecessary checks were being performed on if the event existed before
being removed.
_events starts out as null, so reset to null when emptied.
Checking typeof is a lot cheaper than isArray().
Ability to return just the length of listeners for a given type, using
EventEmitter.listenerCount(emitter, event). This will be a lot cheaper
than creating a copy of the listeners array just to check its length.
Unfortunately, it's just too slow to do this in events.js. Users will
just have to live with not having events named __proto__ or toString.
This reverts commit b48e303af0.
While it's true that error objects have a history of getting snake_case
properties attached by the host system, it's a point of confusion to
Node users that comes up a lot. It's still 'experimental', so best to
change this sooner rather than later.
