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events.js
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events.js
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import { test, summary } from './helpers.js';
import { EventEmitter } from 'ant:events';
console.log('EventEmitter Tests\n');
const ee = new EventEmitter();
let received = null;
ee.on('test', data => {
received = data;
});
ee.emit('test', 'hello');
test('on and emit', received, 'hello');
let count = 0;
ee.on('count', () => count++);
ee.on('count', () => count++);
ee.emit('count');
test('multiple listeners', count, 2);
let onceValue = 0;
ee.once('once', val => {
onceValue = val;
});
ee.emit('once', 42);
ee.emit('once', 100);
test('once only fires once', onceValue, 42);
let removed = false;
const handler = () => {
removed = true;
};
ee.on('remove', handler);
ee.off('remove', handler);
ee.emit('remove');
test('off removes listener', removed, false);
let allRemoved = 0;
ee.on('all', () => allRemoved++);
ee.on('all', () => allRemoved++);
ee.removeAllListeners('all');
ee.emit('all');
test('removeAllListeners', allRemoved, 0);
test('listenerCount', ee.listenerCount('count'), 2);
const names = ee.eventNames();
test('eventNames includes count', names.includes('count'), true);
const ee2 = new EventEmitter();
let args = [];
ee2.on('multi', (a, b, c) => {
args = [a, b, c];
});
ee2.emit('multi', 1, 2, 3);
test('multiple emit args', args.join(','), '1,2,3');
const ee3 = new EventEmitter();
test('emit returns false with no listeners', ee3.emit('none'), false);
ee3.on('exists', () => {});
test('emit returns true with listeners', ee3.emit('exists'), true);
const ee4 = new EventEmitter();
const chain = ee4
.on('a', () => {})
.once('b', () => {})
.off('b', () => {});
test('methods return this for chaining', chain, ee4);
const ee5 = new EventEmitter();
let aliasCount = 0;
ee5.addListener('alias', () => aliasCount++);
ee5.emit('alias');
test('addListener alias works', aliasCount, 1);
const ee6 = new EventEmitter();
let removeAliasVal = 0;
const removeAliasHandler = () => {
removeAliasVal = 1;
};
ee6.on('rem', removeAliasHandler);
ee6.removeListener('rem', removeAliasHandler);
ee6.emit('rem');
test('removeListener alias works', removeAliasVal, 0);
const ee7 = new EventEmitter();
let onceCount = 0;
ee7.once('multi-once', () => onceCount++);
ee7.once('multi-once', () => onceCount++);
ee7.emit('multi-once');
test('multiple once listeners fire', onceCount, 2);
ee7.emit('multi-once');
test('multiple once listeners only fire once', onceCount, 2);
const ee8 = new EventEmitter();
test('listenerCount for non-existent event', ee8.listenerCount('nope'), 0);
const ee9 = new EventEmitter();
const h = () => {};
ee9.on('temp', h);
ee9.off('temp', h);
test('eventNames excludes removed events', ee9.eventNames().includes('temp'), false);
const eeA = new EventEmitter();
const eeB = new EventEmitter();
let aVal = 0,
bVal = 0;
eeA.on('x', () => aVal++);
eeB.on('x', () => bVal++);
eeA.emit('x');
test('separate instances are isolated (A)', aVal, 1);
test('separate instances are isolated (B)', bVal, 0);
console.log('\nEventTarget Tests\n');
const et = new EventTarget();
let etReceived = null;
et.addEventListener('click', e => {
etReceived = e.type;
});
et.dispatchEvent(new Event('click'));
test('EventTarget addEventListener and dispatchEvent', etReceived, 'click');
let etEvent = null;
const et2 = new EventTarget();
et2.addEventListener('custom', e => {
etEvent = e;
});
et2.dispatchEvent(new CustomEvent('custom', { detail: { foo: 'bar' } }));
test('event.type', etEvent.type, 'custom');
test('event.target is EventTarget', etEvent.target, et2);
test('event.detail', etEvent.detail.foo, 'bar');
const et3 = new EventTarget();
let et3Val = 0;
const et3Handler = () => {
et3Val++;
};
et3.addEventListener('rem', et3Handler);
et3.removeEventListener('rem', et3Handler);
et3.dispatchEvent(new Event('rem'));
test('EventTarget removeEventListener', et3Val, 0);
const et4 = new EventTarget();
let et4Count = 0;
et4.addEventListener('once', () => et4Count++, { once: true });
et4.dispatchEvent(new Event('once'));
et4.dispatchEvent(new Event('once'));
test('EventTarget once option', et4Count, 1);
console.log('\nGlobal Event Tests\n');
let globalReceived = null;
addEventListener('global-test', e => {
globalReceived = e.type;
});
dispatchEvent(new Event('global-test'));
test('global addEventListener and dispatchEvent', globalReceived, 'global-test');
let globalRemoved = 0;
const globalHandler = () => {
globalRemoved++;
};
addEventListener('global-rem', globalHandler);
removeEventListener('global-rem', globalHandler);
dispatchEvent(new Event('global-rem'));
test('global removeEventListener', globalRemoved, 0);
console.log('\nCustomEvent Tests\n');
const ce1 = new CustomEvent('ping');
test('CustomEvent type', ce1.type, 'ping');
test('CustomEvent detail defaults to null', ce1.detail, null);
const ce2 = new CustomEvent('animalfound', { detail: { name: 'cat' } });
test('CustomEvent detail', ce2.detail.name, 'cat');
let ceReceived = null;
const et5 = new EventTarget();
et5.addEventListener('animalfound', e => {
ceReceived = e.detail.name;
});
et5.dispatchEvent(ce2);
test('EventTarget dispatchEvent with CustomEvent', ceReceived, 'cat');
let ceGlobal = null;
addEventListener('custom-global', e => {
ceGlobal = e.detail.value;
});
dispatchEvent(new CustomEvent('custom-global', { detail: { value: 42 } }));
test('global dispatchEvent with CustomEvent', ceGlobal, 42);
const ce3 = new CustomEvent('tagged');
test('CustomEvent Symbol.toStringTag', Object.prototype.toString.call(ce3), '[object CustomEvent]');
summary();

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events.js (5 KB)

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