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emitz.js
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emitz.js
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'use strict';
let Emitter = function (targetObject = {}) {
if (!targetObject || typeof targetObject !== 'object' || Array.isArray(targetObject)) {
throw new Error('Whoops! You must provide a target object');
}
let _emitz = {
events: {},
on: function (name, callback) {
if (!this.events[name]) {
this.events[name] = [];
}
this.events[name].push(callback);
},
once: function (name, callback) {
let self = this;
let callbackWrapper = function () {
self.off(name, callbackWrapper);
callback();
};
this.on(name, callbackWrapper);
},
emit: function (name, ...args) {
if (!this.events[name]) {
console.warn(`${name} event not registered!`);
return null;
} else {
this.events[name].forEach(listener => listener(...args));
}
},
off: function (name, listenerToUnregister) {
if (!name || !listenerToUnregister) {
console.warn('Missing required arguments');
return null;
}
if (!this.events[name]) {
console.warn(`${name} event not registered on object it was called on!`);
return null;
}
if (!this.events[name].includes(listenerToUnregister)) {
console.warn(`${listenerToUnregister.name} not a registered listener of ${name} event!`);
return null;
}
this.events[name] = this.events[name].filter(registeredHandler => registeredHandler !== listenerToUnregister);
console.info(`${listenerToUnregister.name} listener unregistered from ${name} event`);
},
nuke: function (name) {
if (!name || !this.events[name]) {
console.warn(`Missing event name or event does not exist!`);
return null;
}
this.events[name] = [];
}
};
return Object.assign({}, targetObject, _emitz);
};
module.exports = Emitter;