Created
April 26, 2019 14:13
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/** | |
* A basic pub-sub mechanism for sibling component communication | |
* | |
* TODO - adopt standard flexipage sibling communication mechanism when it's available. | |
*/ | |
const events = {}; | |
const samePageRef = (pageRef1, pageRef2) => { | |
const obj1 = pageRef1.attributes; | |
const obj2 = pageRef2.attributes; | |
return Object.keys(obj1) | |
.concat(Object.keys(obj2)) | |
.every(key => { | |
return obj1[key] === obj2[key]; | |
}); | |
}; | |
/** | |
* Registers a callback for an event | |
* @param {string} eventName - Name of the event to listen for. | |
* @param {function} callback - Function to invoke when said event is fired. | |
* @param {object} thisArg - The value to be passed as the this parameter to the callback function is bound. | |
*/ | |
const registerListener = (eventName, callback, thisArg) => { | |
// Checking that the listener has a pageRef property. We rely on that property for filtering purpose in fireEvent() | |
if (!thisArg.pageRef) { | |
throw new Error( | |
'pubsub listeners need a "@wire(CurrentPageReference) pageRef" property' | |
); | |
} | |
if (!events[eventName]) { | |
events[eventName] = []; | |
} | |
const duplicate = events[eventName].find(listener => { | |
return listener.callback === callback && listener.thisArg === thisArg; | |
}); | |
if (!duplicate) { | |
events[eventName].push({ callback, thisArg }); | |
} | |
}; | |
/** | |
* Unregisters a callback for an event | |
* @param {string} eventName - Name of the event to unregister from. | |
* @param {function} callback - Function to unregister. | |
* @param {object} thisArg - The value to be passed as the this parameter to the callback function is bound. | |
*/ | |
const unregisterListener = (eventName, callback, thisArg) => { | |
if (events[eventName]) { | |
events[eventName] = events[eventName].filter( | |
listener => | |
listener.callback !== callback || listener.thisArg !== thisArg | |
); | |
} | |
}; | |
/** | |
* Unregisters all event listeners bound to an object. | |
* @param {object} thisArg - All the callbacks bound to this object will be removed. | |
*/ | |
const unregisterAllListeners = thisArg => { | |
Object.keys(events).forEach(eventName => { | |
events[eventName] = events[eventName].filter( | |
listener => listener.thisArg !== thisArg | |
); | |
}); | |
}; | |
/** | |
* Fires an event to listeners. | |
* @param {object} pageRef - Reference of the page that represents the event scope. | |
* @param {string} eventName - Name of the event to fire. | |
* @param {*} payload - Payload of the event to fire. | |
*/ | |
const fireEvent = (pageRef, eventName, payload) => { | |
if (events[eventName]) { | |
const listeners = events[eventName]; | |
listeners.forEach(listener => { | |
if (samePageRef(pageRef, listener.thisArg.pageRef)) { | |
try { | |
listener.callback.call(listener.thisArg, payload); | |
} catch (error) { | |
// fail silently | |
} | |
} | |
}); | |
} | |
}; | |
export { | |
registerListener, | |
unregisterListener, | |
unregisterAllListeners, | |
fireEvent | |
}; |
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