95 lines
1.6 KiB
JavaScript
95 lines
1.6 KiB
JavaScript
/*!
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* ee-first
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* Copyright(c) 2014 Jonathan Ong
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* MIT Licensed
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*/
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'use strict'
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/**
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* Module exports.
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* @public
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*/
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module.exports = first
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/**
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* Get the first event in a set of event emitters and event pairs.
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*
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* @param {array} stuff
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* @param {function} done
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* @public
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*/
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function first(stuff, done) {
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if (!Array.isArray(stuff))
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throw new TypeError('arg must be an array of [ee, events...] arrays')
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var cleanups = []
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for (var i = 0; i < stuff.length; i++) {
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var arr = stuff[i]
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if (!Array.isArray(arr) || arr.length < 2)
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throw new TypeError('each array member must be [ee, events...]')
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var ee = arr[0]
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for (var j = 1; j < arr.length; j++) {
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var event = arr[j]
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var fn = listener(event, callback)
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// listen to the event
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ee.on(event, fn)
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// push this listener to the list of cleanups
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cleanups.push({
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ee: ee,
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event: event,
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fn: fn,
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})
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}
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}
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function callback() {
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cleanup()
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done.apply(null, arguments)
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}
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function cleanup() {
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var x
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for (var i = 0; i < cleanups.length; i++) {
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x = cleanups[i]
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x.ee.removeListener(x.event, x.fn)
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}
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}
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function thunk(fn) {
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done = fn
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}
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thunk.cancel = cleanup
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return thunk
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}
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/**
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* Create the event listener.
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* @private
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*/
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function listener(event, done) {
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return function onevent(arg1) {
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var args = new Array(arguments.length)
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var ee = this
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var err = event === 'error'
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? arg1
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: null
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// copy args to prevent arguments escaping scope
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for (var i = 0; i < args.length; i++) {
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args[i] = arguments[i]
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}
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done(err, ee, event, args)
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}
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}
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