<p>Detects if a file is binary in Node.js using promises. Similar to <a href="http://stackoverflow.com/questions/899206/how-does-perl-know-a-file-is-binary">Perl's <code>-B</code> switch</a>, in that:</p>
<ul>
<li>it reads the first few thousand bytes of a file</li>
<li>checks for a <code>null</code> byte; if it's found, it's binary</li>
<li>flags non-ASCII characters. After a certain number of "weird" characters, the file is flagged as binary</li>
</ul>

<p>Much of the logic is pretty much ported from <a href="https://github.com/ggreer/the_silver_searcher">ag</a>.</p>

<p>Note: if the file doesn't exist or is a directory, an error is thrown.</p>

<h3>Installation</h3>

<pre><code>
npm install isbinaryfile
</code></pre>

<h3>Usage</h3>

<p>Returns <code>Promise<boolean></code> (or just <code>boolean</code> for <code>*Sync</code>). <code>true</code> if the file is binary, <code>false</code> otherwise.</p>

<h4>isBinaryFile(filepath)</h4>

<ul>
<li><code>filepath</code> - a <code>string</code> indicating the path to the file.</li>
</ul>

<h4>isBinaryFile(bytes[, size])</h4>

<ul>
<li><code>bytes</code> - a <code>Buffer</code> of the file's contents.</li>
<li><code>size</code> - an optional <code>number</code> indicating the file size.</li>
</ul>

<h4>isBinaryFileSync(filepath)</h4>

<ul>
<li><code>filepath</code> - a <code>string</code> indicating the path to the file.</li>
</ul>

<h4>isBinaryFileSync(bytes[, size])</h4>

<ul>
<li><code>bytes</code> - a <code>Buffer</code> of the file's contents.</li>
<li><code>size</code> - an optional <code>number</code> indicating the file size.</li>
</ul>

<h4>Examples</h4>

<p>Here's an arbitrary usage:</p>

<pre><code>
const isBinaryFile = require("isbinaryfile").isBinaryFile;
const fs = require("fs");

const filename = "fixtures/pdf.pdf";
const data = fs.readFileSync(filename);
const stat = fs.lstatSync(filename);

isBinaryFile(data, stat.size).then((result) => {
if (result) {
console.log("It is binary!")
}
else {
console.log("No it is not.")
}
});

const isBinaryFileSync = require("isbinaryfile").isBinaryFileSync;
const bytes = fs.readFileSync(filename);
const size = fs.lstatSync(filename).size;
console.log(isBinaryFileSync(bytes, size)); // true or false
</code></pre>

<h3>Testing</h3>

<p>Run <code>npm install</code>, then run <code>npm test</code>.</p>

<hr>

<p>本文由模极社发布</p>

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<p>哪个方案更实用？欢迎投票讨论。</p>