Yang Guo | 4fd355c | 2019-09-19 08:59:03 | [diff] [blame] | 1 | /*! |
| 2 | * ee-first |
| 3 | * Copyright(c) 2014 Jonathan Ong |
| 4 | * MIT Licensed |
| 5 | */ |
| 6 | |
| 7 | 'use strict' |
| 8 | |
| 9 | /** |
| 10 | * Module exports. |
| 11 | * @public |
| 12 | */ |
| 13 | |
| 14 | module.exports = first |
| 15 | |
| 16 | /** |
| 17 | * Get the first event in a set of event emitters and event pairs. |
| 18 | * |
| 19 | * @param {array} stuff |
| 20 | * @param {function} done |
| 21 | * @public |
| 22 | */ |
| 23 | |
| 24 | function first(stuff, done) { |
| 25 | if (!Array.isArray(stuff)) |
| 26 | throw new TypeError('arg must be an array of [ee, events...] arrays') |
| 27 | |
| 28 | var cleanups = [] |
| 29 | |
| 30 | for (var i = 0; i < stuff.length; i++) { |
| 31 | var arr = stuff[i] |
| 32 | |
| 33 | if (!Array.isArray(arr) || arr.length < 2) |
| 34 | throw new TypeError('each array member must be [ee, events...]') |
| 35 | |
| 36 | var ee = arr[0] |
| 37 | |
| 38 | for (var j = 1; j < arr.length; j++) { |
| 39 | var event = arr[j] |
| 40 | var fn = listener(event, callback) |
| 41 | |
| 42 | // listen to the event |
| 43 | ee.on(event, fn) |
| 44 | // push this listener to the list of cleanups |
| 45 | cleanups.push({ |
| 46 | ee: ee, |
| 47 | event: event, |
| 48 | fn: fn, |
| 49 | }) |
| 50 | } |
| 51 | } |
| 52 | |
| 53 | function callback() { |
| 54 | cleanup() |
| 55 | done.apply(null, arguments) |
| 56 | } |
| 57 | |
| 58 | function cleanup() { |
| 59 | var x |
| 60 | for (var i = 0; i < cleanups.length; i++) { |
| 61 | x = cleanups[i] |
| 62 | x.ee.removeListener(x.event, x.fn) |
| 63 | } |
| 64 | } |
| 65 | |
| 66 | function thunk(fn) { |
| 67 | done = fn |
| 68 | } |
| 69 | |
| 70 | thunk.cancel = cleanup |
| 71 | |
| 72 | return thunk |
| 73 | } |
| 74 | |
| 75 | /** |
| 76 | * Create the event listener. |
| 77 | * @private |
| 78 | */ |
| 79 | |
| 80 | function listener(event, done) { |
| 81 | return function onevent(arg1) { |
| 82 | var args = new Array(arguments.length) |
| 83 | var ee = this |
| 84 | var err = event === 'error' |
| 85 | ? arg1 |
| 86 | : null |
| 87 | |
| 88 | // copy args to prevent arguments escaping scope |
| 89 | for (var i = 0; i < args.length; i++) { |
| 90 | args[i] = arguments[i] |
| 91 | } |
| 92 | |
| 93 | done(err, ee, event, args) |
| 94 | } |
| 95 | } |