Sollicitatievraag bij Meta
Write an emitter class: /* emitter = new Emitter(); // 1. Support subscribing to events. sub = emitter.subscribe('event_name', callback); sub2 = emitter.subscribe('event_name', callback2); // 2. Support emitting events. // This particular example should lead to the `callback` above being invoked with `foo` and `bar` as parameters. emitter.emit('event_name', foo, bar); // 3. Support unsubscribing existing subscriptions by releasing them. sub.release(); // `sub` is the reference returned by `subscribe` above
Antwoord op sollicitatievraag
Anoniem
function Emitter() { this.events = new Map(); } Emitter.prototype.subscribe = function(evtName, callback) { this.events.set(evtName, callback); const self = this; return { release: function() { self.events.delete(evtName); } }; } Emitter.prototype.emit = function(evtName, ...params) { if (this.events.has(evtName)) { const event = this.events.get(evtName); event.call(this, ...params); } } const emitter = new Emitter(); const sub1 = emitter.subscribe('click', (param) => console.log(param)); emitter.emit('click', 'hey1'); emitter.emit('click', 'hey2'); emitter.emit('click', 'hey3'); emitter.emit('click', 'hey4'); sub1.release(); emitter.emit('click', 'hey5'); emitter.emit('click', 'hey7'); emitter.emit('click', 'hey9'); emitter.emit('click', 'hey11');