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index.js
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var hasOwn = Function.call.bind(Object.hasOwnProperty)
var slice = Function.call.bind(Array.prototype.slice)
var concat = Array.prototype.concat.bind(Array.prototype)
var NAME_TYPE_ERR = "Event name should be a string"
var LISTENER_TYPE_ERR = "Event listener should be a function"
module.exports = Concert
/**
* Concert is the main object or *module* that you can inject into your own
* objects to make them observables (also known as *event emitters* or
* *dispatchers*). You can then listen to and trigger events on that object.
*
* ```javascript
* var Concert = require("concert")
* function Galaxy() {}
* for (var name in Concert) Galaxy.prototype[name] = Concert[name]
*
* var galaxy = new Galaxy()
* galaxy.on("secret", console.log)
* galaxy.trigger("secret", 42)
* ```
*
* You can also create a new instance of `Concert` to get a blank object to
* use as an *event bus*.
* ```javascript
* var Concert = require("concert")
* var bus = new Concert
* bus.on("message", console.log)
* bus.trigger("message", "One giant man to step, one small...")
* ```
*
* If you need, you can also rename any `Concert`'s function by just assigning
* them to new names on your object:
* ```javascript
* obj.addEventListener = Concert.on
* obj.emit = Concert.trigger
* obj.removeEventListener = Concert.off
* ```
*
* @class Concert
* @constructor
*/
function Concert() {}
/**
* Add a `listener` for `event`.
* Optionally specify the listener's `this` value. Defaults to the object
* the event was triggered on when left undefined.
* Optionally specify additional arguments to be passed to the listener.
* Returns self.
*
* You can also specify **multiple events** at once by passing an object whose
* keys are event names and values functions. Pass the optional `this` then as
* the 2nd parameter.
*
* Listen to the special `all` event to be called when any event is triggered:
* ```javascript
* obj.on("all", function(event) {})
* ```
*
* The listener will be called with any arguments passed to
* [`trigger`](#Concert.trigger).
*
* @example
* music.on("cowbell", function() { console.log("Cluck!") })
* collection.on({add: view.onAdd, remove: view.onRemove}, view)
* model.on("change:name", view.onChange, view, "name")
*
* @static
* @method on
* @param event
* @param listener
* @param [thisArg]
* @param [arguments...]
*/
Concert.prototype.on = function on(name, fn, thisArg) {
if (name == null) throw new TypeError(NAME_TYPE_ERR)
if (unpack(on, this, arguments)) return this
if (fn == null) throw new TypeError(LISTENER_TYPE_ERR)
var events = this._events
if (events == null || !hasOwn(this, "_events"))
events = create(this, "_events", events)
var fns = events[name]
if (fns == null) fns = events[name] = []
else if (!hasOwn(events, name)) fns = events[name] = fns.slice()
fns.push(slice(arguments, 1))
return this
}
/**
* Like [`on`](#Concert.on), but the listener is guaranteed to be called only
* once.
* Returns self.
*
* @static
* @method once
* @param event
* @param listener
* @param [thisArg]
* @param [arguments...]
*/
Concert.prototype.once = function once(name, fn, thisArg) {
if (name == null) throw new TypeError(NAME_TYPE_ERR)
if (unpack(once, this, arguments)) return this
if (fn == null) throw new TypeError(LISTENER_TYPE_ERR)
function fnOnce() {
"use strict"
Concert.prototype.off.call(this, name, fn)
fn.apply(thisArg === undefined ? this : thisArg, arguments)
}
fnOnce.__func = fn
fnOnce.__this = thisArg
var args = [name, fnOnce, undefined]
if (arguments.length > 3) args.push.apply(args, slice(arguments, 3))
return Concert.prototype.on.apply(this, args)
}
/**
* Remove previously added listeners by event name, by listener, by `thisArg`
* or by any combination.
* Returns self.
*
* You can also specify **multiple events** at once by passing an object whose
* keys are event names and values functions. Pass `thisArg` then as the 2nd
* parameter.
*
* @example
* // Remove all listeners:
* obj.off()
* // Remove listeners listening to event "foo":
* obj.off("foo")
* // Remove listeners fn of event "foo":
* obj.off("foo", fn)
* // Remove listener fn bound to thisArg listening to event "foo":
* obj.off("foo", fn, thisArg)
* // Remove all listeners bound to thisArg:
* obj.off(null, null, thisArg)
* // Remove all listeners fn listening to any event:
* obj.off(null, fn)
* // Remove multiple listeners together:
* obj.off({add: view.onAdd, remove: view.onRemove}, thisArg)
*
* @static
* @method off
* @param event
* @param listener
* @param [thisArg]
*/
Concert.prototype.off = function off(name, fn, thisArg) {
var events = this._events
if (events == null) return this
if (unpack(off, this, arguments)) return this
if (fn == null && thisArg === undefined) {
if (name == null)
// When unbinding everything, just set a new _events. Stops the one in
// the prototype.
define(this, "_events", null)
else if (events[name] != null) {
if (!hasOwn(this, "_events")) events = create(this, "_events", events)
else delete events[name]
// If there are inherited events, mask them with null.
if (name in events) events[name] = null
}
}
else {
if (!hasOwn(this, "_events")) events = create(this, "_events", events)
if (name != null) filter(events, name, fn, thisArg)
else for (name in events) filter(events, name, fn, thisArg)
}
return this
}
/**
* Trigger `event` and optionally pass any extra arguments to the listeners.
* Returns self.
*
* Every event triggering also automatically triggers an `all` event with the
* event name prepended to other arguments.
*
* @example
* obj.trigger("change", 42, {previous: 69})
*
* @static
* @method trigger
* @param event
* @param [arguments...]
*/
Concert.prototype.trigger = function trigger(name) {
var events = this._events
if (events == null) return this
if (events[name] != null) apply(events[name], this, slice(arguments, 1))
if (events.all != null) apply(events.all, this, arguments)
return this
}
Concert.on = Concert.prototype.on
Concert.once = Concert.prototype.once
Concert.off = Concert.prototype.off
Concert.trigger = Concert.prototype.trigger
function unpack(on, self, args) {
var obj = args[0]
if (obj == null || typeof obj != "object") return false
var name
if (args.length > 2) {
var argsArray = slice(args, 1)
for (name in obj) on.apply(self, concat(name, obj[name], argsArray))
}
else for (name in obj) on.call(self, name, obj[name], args[1])
return true
}
function define(obj, name, value) {
Object.defineProperty(obj, name, {value: value, configurable: 1, writable: 1})
return value
}
function create(obj, name, prototype) {
return define(obj, name, Object.create(prototype || null))
}
function filter(events, name, fn, thisArg) {
var fns = events[name]
if (fns == null) return
fns = fns.filter(function(args) {
if (fn != null && !hasFunction(args, fn)) return true
if (thisArg !== undefined && !hasThis(args, thisArg)) return true
return false
})
if (fns.length == 0) {
delete events[name]
if (name in events) events[name] = null
}
else events[name] = fns
}
function hasFunction(args, fn) {
return args[0] === fn || args[0].__func === fn
}
function hasThis(args, thisArg) {
return (args[0].__this || args[1]) === thisArg
}
function apply(fns, thisArg, args) {
for (var i = 0, l = fns.length; i < l; ++i) {
var fn = fns[i]
var argsArray = fn.length > 2 ? fn.slice(2) : null
if (argsArray == null) argsArray = args
else if (args.length > 0) argsArray.push.apply(argsArray, args)
fn[0].apply(fn[1] === undefined ? thisArg : fn[1], argsArray)
}
}