Skip to content

events: support event handlers #33646

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
wants to merge 3 commits into from
Closed

events: support event handlers #33646

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
89eaf9c
events: support event handlers
benjamingr May 29, 2020
8ac4425
fixup! lint
benjamingr May 29, 2020
076b122
Update test/parallel/test-eventtarget.js
benjamingr Jun 21, 2020
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
21 changes: 19 additions & 2 deletions lib/internal/event_target.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -445,10 +445,27 @@ function emitUnhandledRejectionOrErr(that, err, event) {
process.emit('error', err, event);
}

// EventEmitter-ish API:

function defineEventHandler(emitter, name) {
// 8.1.5.1 Event handlers - basically `on[eventName]` attributes
let eventHandlerValue;
Object.defineProperty(emitter, `on${name}`, {
get() {
return eventHandlerValue;
},
set(value) {
if (eventHandlerValue) {
emitter.removeEventListener(name, eventHandlerValue);
}
if (typeof value === 'function') {
emitter.addEventListener(name, value);
}
eventHandlerValue = value;
}
});
}
module.exports = {
Event,
EventTarget,
NodeEventTarget,
defineEventHandler,
};
34 changes: 34 additions & 0 deletions test/parallel/test-eventtarget.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@ const {
Event,
EventTarget,
NodeEventTarget,
defineEventHandler
} = require('internal/event_target');

const {
Expand Down Expand Up @@ -439,3 +440,36 @@ ok(EventTarget);
const event = new Event('');
strictEqual(event.toString(), '[object Event]');
}
{
const target = new EventTarget();
defineEventHandler(target, 'foo');
target.onfoo = common.mustCall();
target.dispatchEvent(new Event('foo'));
}
{
const target = new EventTarget();
defineEventHandler(target, 'foo');
let count = 0;
target.onfoo = () => count++;
target.onfoo = common.mustCall(() => count++);
target.dispatchEvent(new Event('foo'));
strictEqual(count, 1);
}
{
const target = new EventTarget();
defineEventHandler(target, 'foo');
let count = 0;
target.addEventListener('foo', () => count++);
target.onfoo = common.mustCall(() => count++);
target.dispatchEvent(new Event('foo'));
strictEqual(count, 2);
}
{
const target = new EventTarget();
defineEventHandler(target, 'foo');
const fn = common.mustNotCall();
target.onfoo = fn;
strictEqual(target.onfoo, fn);
target.onfoo = null;
target.dispatchEvent(new Event('foo'));
}