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c24ace801b
GitOrigin-RevId: 7a0d45e17d9905fa75569e2d19ca59caa4a41565
68 lines
1.8 KiB
JavaScript
68 lines
1.8 KiB
JavaScript
// Simple event emitter implementation, but has a slightly unusual API for
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// removing specific listeners. If a specific listener needs to be removed
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// (instead of all listeners), then it needs to use a "namespace":
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// Create a listener on the foo event with bar namespace: .on 'foo.bar'
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// Trigger all events for the foo event (including namespaces): .trigger 'foo'
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// Remove all listeners for the foo event (including namespaces): .off 'foo'
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// Remove a listener for the foo event with the bar namespace: .off 'foo.bar'
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export default class EventEmitter {
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constructor() {
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this.events = {}
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}
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on(event, callback) {
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if (!this.events) {
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this.events = {}
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}
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let namespace
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;[event, namespace] = Array.from(event.split('.'))
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if (!this.events[event]) {
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this.events[event] = []
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}
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this.events[event].push({
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callback,
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namespace,
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})
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}
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off(event, cb) {
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if (!this.events) {
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this.events = {}
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}
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if (event) {
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let namespace
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;[event, namespace] = event.split('.')
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if (!this.events[event]) {
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this.events[event] = []
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}
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if (cb) {
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this.events[event] = this.events[event].filter(e => e.callback !== cb)
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} else if (!namespace) {
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// Clear all listeners for event
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delete this.events[event]
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} else {
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// Clear only namespaced listeners
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this.events[event] = this.events[event].filter(
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e => e.namespace !== namespace
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)
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}
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} else {
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// Remove all listeners
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this.events = {}
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}
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}
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trigger(event, ...args) {
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if (!this.events) {
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this.events = {}
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}
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if (this.events[event]) {
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this.events[event].forEach(e => e.callback(...args))
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}
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}
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emit(...args) {
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this.trigger(...args)
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}
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}
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