<p>![ci][ci-url]</p>
<p>[![npm version][npm-badge]][npm-url]</p>

<p>Fast, in memory work queue.</p>

<p>Benchmarks (1 million tasks):</p>

<ul>
<li>setImmediate: 812ms</li>
<li>fastq: 854ms</li>
<li>async.queue: 1298ms</li>
<li>neoAsync.queue: 1249ms</li>
</ul>

<p>Obtained on node 12.16.1, on a dedicated server.</p>

<p>If you need zero-overhead series function call, check out</p>
<p><a href="http://npm.im/fastseries">fastseries</a>. For zero-overhead parallel</p>
<p>function call, check out <a href="http://npm.im/fastparallel">fastparallel</a>.</p>

<ul>
<li><a href="#install">Installation</a></li>
<li><a href="#usage">Usage</a></li>
<li><a href="#api">API</a></li>
<li><a href="#license">Licence &amp; copyright</a></li>
</ul>

<h3>Install</h3>

<p><code>npm i fastq --save</code></p>

<h3>Usage (callback API)</h3>

<pre><code>
'use strict'

const queue = require('fastq')(worker, 1)

queue.push(42, function (err, result) {
if (err) { throw err }
console.log('the result is', result)
})

function worker (arg, cb) {
cb(null, arg * 2)
}
</code></pre>

<h3>Usage (promise API)</h3>

<pre><code>
const queue = require('fastq').promise(worker, 1)

async function worker (arg) {
return arg * 2
}

async function run () {
const result = await queue.push(42)
console.log('the result is', result)
}

run()
</code></pre>

<h4>Setting "this"</h4>

<pre><code>
'use strict'

const that = { hello: 'world' }
const queue = require('fastq')(that, worker, 1)

queue.push(42, function (err, result) {
if (err) { throw err }
console.log(this)
console.log('the result is', result)
})

function worker (arg, cb) {
console.log(this)
cb(null, arg * 2)
}
</code></pre>

<h4>Using with TypeScript (callback API)</h4>

<pre><code>
'use strict'

import * as fastq from "fastq";
import type { queue, done } from "fastq";

type Task = {
id: number
}

const q: queue<Task> = fastq(worker, 1)

q.push({ id: 42})

function worker (arg: Task, cb: done) {
console.log(arg.id)
cb(null)
}
</code></pre>

<h4>Using with TypeScript (promise API)</h4>

<pre><code>
'use strict'

import * as fastq from "fastq";
import type { queueAsPromised } from "fastq";

type Task = {
id: number
}

const q: queueAsPromised<Task> = fastq.promise(asyncWorker, 1)

q.push({ id: 42}).catch((err) => console.error(err))

async function asyncWorker (arg: Task): Promise<void> {
// No need for a try-catch block, fastq handles errors automatically
console.log(arg.id)
}
</code></pre>

<h3>API</h3>

<ul>
<li><a href="#fastqueue"><code>fastqueue()</code></a></li>
<li><a href="#push"><code>queue#<b>push()</b></code></a></li>
<li><a href="#unshift"><code>queue#<b>unshift()</b></code></a></li>
<li><a href="#pause"><code>queue#<b>pause()</b></code></a></li>
<li><a href="#resume"><code>queue#<b>resume()</b></code></a></li>
<li><a href="#idle"><code>queue#<b>idle()</b></code></a></li>
<li><a href="#length"><code>queue#<b>length()</b></code></a></li>
<li><a href="#getQueue"><code>queue#<b>getQueue()</b></code></a></li>
<li><a href="#kill"><code>queue#<b>kill()</b></code></a></li>
<li><a href="#killAndDrain"><code>queue#<b>killAndDrain()</b></code></a></li>
<li><a href="#error"><code>queue#<b>error()</b></code></a></li>
<li><a href="#concurrency"><code>queue#<b>concurrency</b></code></a></li>
<li><a href="#drain"><code>queue#<b>drain</b></code></a></li>
<li><a href="#empty"><code>queue#<b>empty</b></code></a></li>
<li><a href="#saturated"><code>queue#<b>saturated</b></code></a></li>
<li><a href="#promise"><code>fastqueue.promise()</code></a></li>
</ul>

<hr>
<p><a name="fastqueue"></a></p>
<h4>fastqueue([that], worker, concurrency)</h4>

<p>Creates a new queue.</p>

<p>Arguments:</p>

<ul>
<li><code>that</code>, optional context of the <code>worker</code> function.</li>
<li><code>worker</code>, worker function, it would be called with <code>that</code> as <code>this</code>,</li>
</ul>
<p> if that is specified.</p>
<ul>
<li><code>concurrency</code>, number of concurre</li>
</ul>

<hr>
<p>踩过坑的来评论区说说。</p>