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August 29, 2015 14:25
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Simple delegated event handling.
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| (function() { | |
| const events = new Map(); | |
| const stopped = new WeakMap(); | |
| function before(subject, verb, fn) { | |
| const source = subject[verb]; | |
| subject[verb] = function() { | |
| fn.apply(subject, arguments); | |
| return source.apply(subject, arguments); | |
| }; | |
| return subject; | |
| } | |
| function dispatch(observers, event) { | |
| before(event, 'stopImmediatePropagation', stopped.set.bind(stopped, event)); | |
| const matches = observers.matches(event.target); | |
| for (var i = 0, length = matches.length; i < length; i++) { | |
| if (stopped.has(event)) break; | |
| matches[i].data.call(event.target, event); | |
| } | |
| } | |
| this.on = function(name, selector, fn) { | |
| var observers = events.get(name); | |
| if (!observers) { | |
| observers = new SelectorSet(); | |
| events.set(name, observers); | |
| document.addEventListener(name, dispatch.bind(null, observers), false); | |
| } | |
| observers.add(selector, fn); | |
| }; | |
| this.off = function(name, selector, fn) { | |
| const observers = events.get(name); | |
| if (observers) { | |
| observers.remove(selector, fn); | |
| } | |
| }; | |
| this.fire = function(target, name, detail) { | |
| return target.dispatchEvent( | |
| new CustomEvent(name, { | |
| bubbles: true, | |
| cancelable: true, | |
| detail: detail | |
| }) | |
| ); | |
| }; | |
| }).call($); | |
| $.on('click', '.js-toggle-lang-stats', function(event) { | |
| document.querySelector('.js-stats-switcher-viewport').classList.toggle('is-revealing-lang-stats'); | |
| event.preventDefault(); | |
| }); | |
| $.fire(document.body, 'validation:change', {id: 42, login: 'hubot'}); |
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Years off, but I'd expect to see an official replacement for addEventListener someday. Some ideas standards people are talking about.
http://www.xanthir.com/b4PV0
https://github.com/zenparsing/es-observable