EE First——模具行业从业者必备知识手册

system 2

<h2>EE First</h2>

[![NPM version][npm-image]][npm-url]
[![Build status][travis-image]][travis-url]
[![Test coverage][coveralls-image]][coveralls-url]
[![License][license-image]][license-url]
[![Downloads][downloads-image]][downloads-url]
[![Gittip][gittip-image]][gittip-url]

Get the first event in a set of event emitters and event pairs,
then clean up after itself.

<h3>Install</h3>

<pre><code>
$ npm install ee-first
</code></pre>

<pre><code>
var first = require('ee-first')
</code></pre>

<h4>first(arr, listener)</h4>

Invoke <code>listener</code> on the first event from the list specified in <code>arr</code>. <code>arr</code> is
an array of arrays, with each array in the format <code>[ee, ...event]</code>. <code>listener</code>
will be called only once, the first time any of the given events are emitted. If
<code>error</code> is one of the listened events, then if that fires first, the <code>listener</code>
will be given the <code>err</code> argument.

The <code>listener</code> is invoked as <code>listener(err, ee, event, args)</code>, where <code>err</code> is the
first argument emitted from an <code>error</code> event, if applicable; <code>ee</code> is the event
emitter that fired; <code>event</code> is the string event name that fired; and <code>args</code> is an
array of the arguments that were emitted on the event.

<pre><code>
var ee1 = new EventEmitter()
var ee2 = new EventEmitter()

first([
[ee1, 'close', 'end', 'error'],
[ee2, 'error']
], function (err, ee, event, args) {
// listener invoked
})
</code></pre>

#### .cancel()

The group of listeners can be cancelled before being invoked and have all the event
listeners removed from the underlying event emitters.

<pre><code>
var thunk = first([
[ee1, 'close', 'end', 'error'],
[ee2, 'error']
], function (err, ee, event, args) {
// listener invoked
})

// cancel and clean up
thunk.cancel()
</code></pre>

[npm-image]: https://img.shields.io/npm/v/ee-first.svg?style=flat-square
[npm-url]: https://npmjs.org/package/ee-first
[github-tag]: http://img.shields.io/github/tag/jonathanong/ee-first.svg?style=flat-square
[github-url]: https://github.com/jonathanong/ee-first/tags
[travis-image]: https://img.shields.io/travis/jonathanong/ee-first.svg?style=flat-square
[travis-url]: https://travis-ci.org/jonathanong/ee-first
[coveralls-image]: https://img.shields.io/coveralls/jonathanong/ee-first.svg?style=flat-square
[coveralls-url]: https://coveralls.io/r/jonathanong/ee-first?branch=master
[license-image]: http://img.shields.io/npm/l/ee-first.svg?style=flat-square
[license-url]: LICENSE.md
[downloads-image]: http://img.shields.io/npm/dm/ee-first.svg?style=flat-square
[downloads-url]: https://npmjs.org/package/ee-first
[gittip-image]: https://img.shields.io/gittip/jonathanong.svg?style=flat-square
[gittip-url]: https://www.gittip.com/jonathanong/

<hr>

本文由模极社发布

<table>
<tr><td>分类</td><td>要点</td><td>建议/说明</td></tr>
<tr><td>核心概念</td><td>EE First</td><td>详见正文</td></tr>
<tr><td>操作步骤</td><td>EE First</td><td>详见正文</td></tr>
<tr><td>注意事项</td><td>EE First</td><td>详见正文</td></tr>
<tr><td>适用场景</td><td>EE First</td><td>详见正文</td></tr>
<tr><td>常见问题</td><td>EE First</td><td>详见正文</td></tr>
</table>

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