43 lines
1.4 KiB
JavaScript
43 lines
1.4 KiB
JavaScript
/**
|
|
* Returns an EventEmitter that proxies events from the given event emitter
|
|
* @param {any} eventEmitter
|
|
* @param {object} listeners - The listeners to proxy to
|
|
* @returns {any}
|
|
*/
|
|
module.exports = function createEventEmitterProxy (eventEmitter, listeners) {
|
|
let target = eventEmitter
|
|
const eventHandlers = listeners || {}
|
|
const proxy = /** @type {any} */ (new Proxy({}, {
|
|
get: (_, name) => {
|
|
// intercept listeners
|
|
if (name === 'on') return addListener
|
|
if (name === 'setTarget') return setTarget
|
|
if (name === 'proxyEventHandlers') return eventHandlers
|
|
return (/** @type {any} */ (target))[name]
|
|
},
|
|
set: (_, name, value) => {
|
|
target[name] = value
|
|
return true
|
|
},
|
|
}))
|
|
function setTarget (/** @type {EventEmitter} */ eventEmitter) {
|
|
target = eventEmitter
|
|
// migrate listeners
|
|
Object.keys(eventHandlers).forEach((name) => {
|
|
/** @type {Array<Function>} */ (eventHandlers[name]).forEach((handler) => target.on(name, handler))
|
|
})
|
|
}
|
|
/**
|
|
* Attaches a function to be called whenever the specified event is emitted
|
|
* @param {string} name
|
|
* @param {Function} handler
|
|
*/
|
|
function addListener (name, handler) {
|
|
if (!eventHandlers[name]) eventHandlers[name] = []
|
|
eventHandlers[name].push(handler)
|
|
target.on(name, handler)
|
|
}
|
|
if (listeners) proxy.setTarget(eventEmitter)
|
|
return proxy
|
|
}
|