diff --git a/listener.js b/listener.js index ffe39ac..5aafd0f 100644 --- a/listener.js +++ b/listener.js @@ -9,28 +9,33 @@ Example: */ const registry = new Map() - export const listener = (target={}) => { - let callbacks = new Map() - function listen(prop, callback) { - if ("object" == typeof prop && "forEach" in prop) { - prop.forEach(prop => this.listen(prop, callback)) - } else if (callback) { - let list = callbacks.get(prop) - if (!list) callbacks.set(prop, list=[]) - list.push(callback) + const callbacks = new Map() + const methods = Object.create(null) + methods.listen = function(name, fn, {once=false}={}) { + const callback = once + ? (...args) => { this.forget(name, callback); return fn(...args) } + : fn + let set = callbacks.get(name) ?? new Set() + callbacks.set(name, set) + set.add(callback) + } + methods.forget = function(name, callback) { + if (callback) { + const set = callbacks.get(name) + if (set) set.delete(callback) } else { - callbacks.delete(prop) + callbacks.delete(name) } } let proxy = new Proxy(target, { set: (target, prop, value) => { - if (callbacks.has("*")) callbacks.get("*").forEach(callback => callback(value, prop, target[prop])) - if (callbacks.has(prop)) callbacks.get(prop).forEach(callback => callback(value, prop, target[prop])) + if (callbacks.has(null)) callbacks.get(null).forEach(callback => callback(value, target[prop], prop)) + if (callbacks.has(prop)) callbacks.get(prop).forEach(callback => callback(value, target[prop], prop)) return Reflect.set(target, prop, value) }, - get: (target, prop, value) => prop=="listen" - ? listen + get: (target, prop, value) => prop in methods + ? methods[prop] : target[prop] }) registry.set(proxy, target) @@ -39,16 +44,4 @@ export const listener = (target={}) => { listener.raw = proxy => registry.get(proxy) -export const text = (listener, prop) => { - if (prop) { - const node = document.createTextNode(listener[prop]) - listener.listen(prop, data => node.data = data) - return node - } else { - return new Proxy(listener, { - get: (target, prop, receiver) => text(listener, prop) - }) - } -} - export default listener