blocks|key|3007211|text|需要将编码设置为response，而不是request：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3007212|req+=+https.request(options,+function(res)+{
++++res.setEncoding('binary');

++++var+data+=+[+];

++++res.on('data',+function(chunk)+{
++++++++data.push(chunk);
++++});
++++res.on('end',+function()+{
++++++++var+binary+=+Buffer.concat(data);
++++++++//+binary+is+your+data
++++});
++++res.on('error',+function(err)+{
++++++++console.log("Error+during+HTTP+request");
++++++++console.log(err.message);
++++});
});|code-block|syntax|javascript|3007213|以下是有用的答案：Writing+image+to+local+server|offset|length|3007214|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/5294470/node-js-writing-image-to-local-server^0|0|0|9|T|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@$I|V|J|W|1|X]]|A|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

You need to set encoding to response, not request:

<pre><code>req = https.request(options, function(res) {
 res.setEncoding('binary');

 var data = [ ];

 res.on('data', function(chunk) {
 data.push(chunk);
 });
 res.on('end', function() {
 var binary = Buffer.concat(data);
 // binary is your data
 });
 res.on('error', function(err) {
 console.log("Error during HTTP request");
 console.log(err.message);
 });
});
</code></pre>

Here is useful answer: <a href="https://stackoverflow.com/questions/5294470/node-js-writing-image-to-local-server">Writing image to local server</a>

blocks|key|184190|text|被接受的答案对我不起作用(例如，将编码设置为二进制)，甚至提出问题的用户也提到它不起作用。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|184191|以下是对我有效的方法，摘自：http://chad.pantherdev.com/node-js-binary-http-streams/|offset|length|184192|http.get(url.parse('http://myserver.com:9999/package'),+function(res)+{
++++var+data+=+[];

++++res.on('data',+function(chunk)+{
++++++++data.push(chunk);
++++}).on('end',+function()+{
++++++++//at+this+point+data+is+an+array+of+Buffers
++++++++//so+Buffer.concat()+can+make+us+a+new+Buffer
++++++++//of+all+of+them+together
++++++++var+buffer+=+Buffer.concat(data);
++++++++console.log(buffer.toString('base64'));
++++});
});|code-block|syntax|javascript|184193|编辑:根据分号的建议进行更新回答|style|BOLD|184194|entityMap|0|LINK|mutability|MUTABLE|url|http://chad.pantherdev.com/node-js-binary-http-streams/^0|0|E|1J|0|0|0|0|C|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|X|8|@]|9|@$D|Y|E|Z|1|10]]|A|$]]|$1|F|3|G|5|H|7|11|8|@]|9|@]|A|$I|J]]|$1|K|3|L|5|6|7|12|8|@$D|13|E|14|M|N]]|9|@]|A|$]]|$1|O|3|-4|5|6|7|15|8|@]|9|@]|A|$]]]|P|$Q|$5|R|S|T|A|$U|V]]]]

The accepted answer did not work for me (i.e., setting encoding to binary), even the user who asked the question mentioned it did not work.

Here's what worked for me, taken from: <a href="http://chad.pantherdev.com/node-js-binary-http-streams/">http://chad.pantherdev.com/node-js-binary-http-streams/</a>

<pre><code>http.get(url.parse('http://myserver.com:9999/package'), function(res) {
 var data = [];

 res.on('data', function(chunk) {
 data.push(chunk);
 }).on('end', function() {
 //at this point data is an array of Buffers
 //so Buffer.concat() can make us a new Buffer
 //of all of them together
 var buffer = Buffer.concat(data);
 console.log(buffer.toString('base64'));
 });
});
</code></pre>

Edit: Update answer following a suggestion by Semicolon

blocks|key|3007298|text|在AWS+Lambda环境中运行在NodeJS+6.10(和8.10,2019年2月测试)上，上面的解决方案都不适合我。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3007299|对我来说起作用的是：|3007300|https.get(opt,+(res)+=>+{
++++res.setEncoding('binary');
++++let+chunks+=+[];

++++res.on('data',+(chunk)+=>+{
++++++++chunks.push(Buffer.from(chunk,+'binary'));
++++});

++++res.on('end',+()+=>+{
++++++++let+binary+=+Buffer.concat(chunks);
++++++++//+binary+is+now+a+Buffer+that+can+be+used+as+Uint8Array+or+as
++++++++//+any+other+TypedArray+for+data+processing+in+NodeJS+or+
++++++++//+passed+on+via+the+Buffer+to+something+else.
++++});
});|code-block|syntax|javascript|3007301|注意res.setEncoding(+'binary')和Buffer.from(chunk，‘binary’)行。一个设置响应编码，另一个从前面指定的编码中提供的字符串创建一个Buffer对象。|3007302|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|N|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|O|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|P|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

Running on NodeJS 6.10(and 8.10, tested in Feb 2019) in the AWS Lambda environment, none of the solutions above worker for me.

What did work for me was the following:

<pre><code>https.get(opt, (res) =&gt; {
 res.setEncoding('binary');
 let chunks = [];

 res.on('data', (chunk) =&gt; {
 chunks.push(Buffer.from(chunk, 'binary'));
 });

 res.on('end', () =&gt; {
 let binary = Buffer.concat(chunks);
 // binary is now a Buffer that can be used as Uint8Array or as
 // any other TypedArray for data processing in NodeJS or 
 // passed on via the Buffer to something else.
 });
});
</code></pre>

Take note the res.setEncoding('binary'); and Buffer.from(chunk, 'binary') lines. One sets the response encoding and the other creates a Buffer object from the string provided in the encoding specified previously.

blocks|key|3007363|text|Pärt+Johanson我希望我能发表评论，只是为了感谢你把我从递归循环中解救出来，我一整天都在撕开我的头发，然后阅读(令人难以置信无用的)节点文档，关于这个，一遍又一遍。找到您的答案后，我深入到文档中，我甚至找不到文档中记录的res.setEncoding方法！这只是两个示例的一部分，在这两个示例中，他们调用res.setEncoding('utf8');，你是在哪里找到它的，或者你是如何找到它的！？|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3007364|由于我没有足够的名气来发表评论，我至少会在我的答案中贡献一些有用的东西:+Pärt+Johanson的答案对我来说是100%25有效的，我只是根据我的需要做了一点调整，因为我正在使用NWJS0.36.4/Node11.0上的nw.Window.get().evalNWBin()下载和评估我的服务器上托管的脚本(并使用nwjc编译)：|3007365|let+opt+=+{...};
let+req+=+require('https').request(opt,+(res)+=>+{
++//+server+error+returned
++if+(200+!==+res.statusCode)+{
++++res.setEncoding('utf8');
++++let+data+=+'';
++++res.on('data',+(strData)+=>+{
++++++data+%2B=+strData;
++++});
++++res.on('end',+()+=>+{
++++++if+(!res.complete)+{
++++++++console.log('Server+error,+incomplete+response:+'+%2B+data);
++++++}+else+{
++++++++console.log('Server+error,+response:+'+%2B+data);
++++++}
++++});
++}
++//+expected+response
++else+{
++++res.setEncoding('binary');
++++let+data+=+[];
++++res.on('data',+(binData)+=>+{
++++++data.push(Buffer.from(binData,+'binary'));
++++});
++++res.on('end',+()+=>+{
++++++data+=+Buffer.concat(data);
++++++if+(!res.complete)+{
++++++++console.log('Request+completed,+incomplete+response,+'+%2B+data.length+%2B+'+bytes+received');
++++++}+else+{
++++++++console.log('Request+completed,+'+%2B+data.length+%2B+'+bytes+received');
++++++++nw.Window.get().evalNWBin(null,+data);
++++++}
++++});
++}
};|code-block|syntax|javascript|3007366|编辑:附注:我发布这篇文章只是为了以防有人想知道如何处理非二进制响应--我的实际代码稍微深入一点，检查响应内容类型标头以解析JSON+(预期失败，即400、401、403)或HTML+(意外失败，即404或500)|3007367|entityMap^0|37|F|4D|O|0|32|R|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]|$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|V|8|@$9|W|A|X|B|C]]|D|@]|E|$]]|$1|H|3|I|5|J|7|Y|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|Z|8|@]|D|@]|E|$]]|$1|O|3|-4|5|6|7|10|8|@]|D|@]|E|$]]]|P|$]]

Pärt Johanson I wish I could comment just to thank you for saving me from the recursive loop I've been in all day of ripping my hair out and then reading the (incredibly unhelpful) node docs on this, over, and over. Upon finding your answer, I went to dig into the docs, and I can't even find the <code>res.setEncoding</code> method documented anywhere! It's just shown as part of two examples, wherein they call <code>res.setEncoding('utf8');</code> Where did you find this or how did you figure it out!?
Since I don't have enough reputation to comment, I'll at least contribute something useful with my answer: Pärt Johanson's answer worked 100% for me, I just tweaked it a bit for my needs because I'm using it to download and eval a script hosted on my server (and compiled with nwjc) using <code>nw.Window.get().evalNWBin()</code> on NWJS 0.36.4 / Node 11.11.0:
<pre><code>let opt = {...};
let req = require('https').request(opt, (res) =&gt; {
 // server error returned
 if (200 !== res.statusCode) {
 res.setEncoding('utf8');
 let data = '';
 res.on('data', (strData) =&gt; {
 data += strData;
 });
 res.on('end', () =&gt; {
 if (!res.complete) {
 console.log('Server error, incomplete response: ' + data);
 } else {
 console.log('Server error, response: ' + data);
 }
 });
 }
 // expected response
 else {
 res.setEncoding('binary');
 let data = [];
 res.on('data', (binData) =&gt; {
 data.push(Buffer.from(binData, 'binary'));
 });
 res.on('end', () =&gt; {
 data = Buffer.concat(data);
 if (!res.complete) {
 console.log('Request completed, incomplete response, ' + data.length + ' bytes received');
 } else {
 console.log('Request completed, ' + data.length + ' bytes received');
 nw.Window.get().evalNWBin(null, data);
 }
 });
 }
};

</code></pre>
Edit: P.S. I posted this just in case anyone wanted to know how to handle a non-binary response -- my actual code goes a little deeper and checks response content type header to parse JSON (intended failure, i.e. 400, 401, 403) or HTML (unexpected failure, i.e. 404 or 500)

blocks|key|184289|text|type|unstyled|depth|inlineStyleRanges|entityRanges|data|184290|不要调用setEncoding()方法，因为on.data回调方法中的by+default,+no+encoding+is+assigned+and+stream+data+will+be+returned+as+Buffer+objects|ordered-list-item|offset|length|style|CODE|184291|Call+Buffer.from()会将chunk值转换为Buffer对象。|184292|184293|http.get('my_url',+(response)+=>+{
++const+chunks+=+[];
++response.on('data',+chunk+=>+chunks.push(Buffer.from(chunk)))+//+Converte+`chunk`+to+a+`Buffer`+object.
++++.on('end',+()+=>+{
++++++const+buffer+=+Buffer.concat(chunks);
++++++console.log(buffer.toString('base64'));
++++});
});|code-block|syntax|javascript|184294|entityMap|0|LINK|mutability|MUTABLE|url|https://nodejs.org/api/stream.html#stream_readable_setencoding_encoding^0|0|4|D|M|7|2Z|6|Z|2E|0|0|5|D|K|5|T|6|0|0|0^^$0|@$1|2|3|-4|4|5|6|X|7|@]|8|@]|9|$]]|$1|A|3|B|4|C|6|Y|7|@$D|Z|E|10|F|G]|$D|11|E|12|F|G]|$D|13|E|14|F|G]]|8|@$D|15|E|16|1|17]]|9|$]]|$1|H|3|I|4|C|6|18|7|@$D|19|E|1A|F|G]|$D|1B|E|1C|F|G]|$D|1D|E|1E|F|G]]|8|@]|9|$]]|$1|J|3|-4|4|5|6|1F|7|@]|8|@]|9|$]]|$1|K|3|L|4|M|6|1G|7|@]|8|@]|9|$N|O]]|$1|P|3|-4|4|5|6|1H|7|@]|8|@]|9|$]]]|Q|$R|$4|S|T|U|9|$V|W]]]]

<ol>
<li>Don't call <code>setEncoding()</code> method, because <a href="https://nodejs.org/api/stream.html#stream_readable_setencoding_encoding" rel="noreferrer">by default, no encoding is assigned and stream data will be returned as <code>Buffer</code> objects</a></li>
<li>Call <code>Buffer.from()</code> in <code>on.data</code> callback method to convert the <code>chunk</code> value to a <code>Buffer</code> object.</li>
</ol>

<pre class="lang-js prettyprint-override"><code>http.get('my_url', (response) =&gt; {
 const chunks = [];
 response.on('data', chunk =&gt; chunks.push(Buffer.from(chunk))) // Converte `chunk` to a `Buffer` object.
 .on('end', () =&gt; {
 const buffer = Buffer.concat(chunks);
 console.log(buffer.toString('base64'));
 });
});
</code></pre>

blocks|key|3007450|text|和这里的其他人一样，我需要处理来自Node.js+HTTP+response+(也称为http.IncomingMessage)的二进制数据块。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3007451|除了Pärt+Johanson的answer及其变体之外，没有一个现有的答案真正适用于我的Electron6项目(在本文发布时与Node.js+12.4.0捆绑在一起)。|3007452|尽管如此，即使使用该解决方案，块也总是作为string对象(而不是预期和期望的Buffer对象)到达response.on('data',+ondata)处理程序。这引起了与Buffer.from(chunk,+'binary')的额外转换。不管我是用response.setEncoding('binary')还是response.setEncoding(null)显式地指定了二进制编码，我都会得到字符串。|3007453|我设法获得原始response块的唯一方法是通过管道将write+Buffer块传输到stream.Writable+的一个实例，在该实例中，我提供了一个自定义的stream.Writable|BOLD|3007454|const+https+=+require('https');
const+{+Writable+}+=+require('stream');

async+function+getBinaryDataAsync(url)+{
++//+start+HTTP+request,+get+binary+response
++const+{+request,+response+}+=+await+new+Promise((resolve,+reject)+=>+{
++++const+request+=+https.request(url,+{+
++++++method:+'GET',+
++++++++headers:+{+
++++++++++'Accept':+'application/pdf',+
++++++++++'Accept-Encoding':+'identity'
++++++++}++++++++
++++++}
++++);

++++request.on('response',+response+=>+
++++++resolve({request,+response}));
++++request.on('error',+reject);
++++request.end();
++});

++//+read+the+binary+response+by+piping+it+to+stream.Writable
++const+buffers+=+await+new+Promise((resolve,+reject)+=>+{

++++response.on('aborted',+reject);
++++response.on('error',+reject);

++++const+chunks+=+[];

++++const+stream+=+new+Writable({
++++++write:+(chunk,+encoding,+notifyComplete)+=>+{
++++++++try+{
++++++++++chunks.push(chunk);
++++++++++notifyComplete();++++++
++++++++}
++++++++catch(error)+{
++++++++++notifyComplete(error);++++++
++++++++}
++++++}
++++});

++++stream.on('error',+reject);
++++stream.on('finish',+()+=>+resolve(chunks));
++++response.pipe(stream);
++});

++const+buffer+=+Buffer.concat(buffers);
++return+buffer.buffer;+//+as+ArrayBuffer
}

async+function+main()+{
++const+arrayBuff+=+await+getBinaryDataAsync('https://download.microsoft.com/download/8/A/4/8A48E46A-C355-4E5C-8417-E6ACD8A207D4/VisualStudioCode-TipsAndTricks-Vol.1.pdf');
++console.log(arrayBuff.byteLength);
};

main().catch(error+=>+console.error(error));|code-block|syntax|javascript|3007455|更新了，当它转向时，这个行为只在我们的Web+API服务器上表现出来。因此，对于我在上面的代码片段中使用的示例网址，response.on('data')实际上工作得很好，并且它不需要流。这很奇怪，虽然这是特定于服务器的，我正在进一步调查它。|3007456|entityMap|0|LINK|mutability|MUTABLE|url|https://nodejs.org/api/http.html#http_class_http_incomingmessage|1|https://stackoverflow.com/a/49600958^0|17|K|17|K|0|0|G|6|1|0|L|6|13|6|1E|R|2F|S|3I|U|4E|Q|0|7|8|R|5|17|F|1N|11|7|8|R|5|X|6|17|F|29|F|0|0|0|3|1M|J|0^^$0|@$1|2|3|4|5|6|7|13|8|@$9|14|A|15|B|C]]|D|@$9|16|A|17|1|18]]|E|$]]|$1|F|3|G|5|6|7|19|8|@]|D|@$9|1A|A|1B|1|1C]]|E|$]]|$1|H|3|I|5|6|7|1D|8|@$9|1E|A|1F|B|C]|$9|1G|A|1H|B|C]|$9|1I|A|1J|B|C]|$9|1K|A|1L|B|C]|$9|1M|A|1N|B|C]|$9|1O|A|1P|B|C]]|D|@]|E|$]]|$1|J|3|K|5|6|7|1Q|8|@$9|1R|A|1S|B|L]|$9|1T|A|1U|B|L]|$9|1V|A|1W|B|L]|$9|1X|A|1Y|B|L]|$9|1Z|A|20|B|C]|$9|21|A|22|B|C]|$9|23|A|24|B|C]|$9|25|A|26|B|C]|$9|27|A|28|B|C]]|D|@]|E|$]]|$1|M|3|N|5|O|7|29|8|@]|D|@]|E|$P|Q]]|$1|R|3|S|5|6|7|2A|8|@$9|2B|A|2C|B|L]|$9|2D|A|2E|B|C]]|D|@]|E|$]]|$1|T|3|-4|5|6|7|2F|8|@]|D|@]|E|$]]]|U|$V|$5|W|X|Y|E|$Z|10]]|11|$5|W|X|Y|E|$Z|12]]]]

As others here, I needed to process binary data chunks from Node.js HTTP response (aka <a href="https://nodejs.org/api/http.html#http_class_http_incomingmessage" rel="nofollow noreferrer"><code>http.IncomingMessage</code></a>).

None of the existing answers really worked for my Electron 6 project (bundled with Node.js 12.4.0, at the time of posting), besides Pärt Johanson's <a href="https://stackoverflow.com/a/49600958">answer</a> and its variants. 

Still, even with that solution, the chunks were always arriving at the <code>response.on('data', ondata)</code> handler as <code>string</code> objects (rather than expected and desired <code>Buffer</code> objects). That incurred extra conversion with <code>Buffer.from(chunk, 'binary')</code>. I was getting strings regardless of whether I explicitly specified binary encoding with <code>response.setEncoding('binary')</code> or <code>response.setEncoding(null)</code>. 

The only way I managed to get the original <code>Buffer</code> chunks was to pipe the <code>response</code> to an instance of <code>stream.Writable</code> where I provide a custom <code>write</code> method:

<pre><code>const https = require('https');
const { Writable } = require('stream');

async function getBinaryDataAsync(url) {
 // start HTTP request, get binary response
 const { request, response } = await new Promise((resolve, reject) =&gt; {
 const request = https.request(url, { 
 method: 'GET', 
 headers: { 
 'Accept': 'application/pdf', 
 'Accept-Encoding': 'identity'
 } 
 }
 );

 request.on('response', response =&gt; 
 resolve({request, response}));
 request.on('error', reject);
 request.end();
 });

 // read the binary response by piping it to stream.Writable
 const buffers = await new Promise((resolve, reject) =&gt; {

 response.on('aborted', reject);
 response.on('error', reject);

 const chunks = [];

 const stream = new Writable({
 write: (chunk, encoding, notifyComplete) =&gt; {
 try {
 chunks.push(chunk);
 notifyComplete(); 
 }
 catch(error) {
 notifyComplete(error); 
 }
 }
 });

 stream.on('error', reject);
 stream.on('finish', () =&gt; resolve(chunks));
 response.pipe(stream);
 });

 const buffer = Buffer.concat(buffers);
 return buffer.buffer; // as ArrayBuffer
}

async function main() {
 const arrayBuff = await getBinaryDataAsync('https://download.microsoft.com/download/8/A/4/8A48E46A-C355-4E5C-8417-E6ACD8A207D4/VisualStudioCode-TipsAndTricks-Vol.1.pdf');
 console.log(arrayBuff.byteLength);
};

main().catch(error =&gt; console.error(error));
</code></pre>

Updated, as it turns, this behavior only manifests for our Web API server. So, <code>response.on('data')</code> actually works well for the sample URL I use in the above code snippet and the stream is not needed for it. It's weird though this is sever-specific, I'm investigating it further.

blocks|key|3007487|text|这里的每个人都在正确的轨道上，但是为了解决这个问题，you++.setEncoding()永远不能。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3007488|如果您调用.setEncoding()，它将创建一个StringDecoder并将其设置为default+decoder。如果您尝试传递null或undefined，则它仍将使用其默认解码器UTF-8创建一个StringDecoder。即使调用.setEncoding('binary')，也等同于调用.setEncoding('latin1')。是的，seriously。|3007489|我希望我可以说您将._readableState.encoding和_readableState.decoder设置回null，但是当您调用.setEncoding()时，缓冲区将被擦除，并替换为以前的解码字符串的二进制编码。这意味着你的数据已经被更改了。|3007490|如果你想“撤销”解码，你必须将数据流重新编码成二进制，如下所示：|3007491|++req.on('data',+(chunk)+=>+{
++++++let+buffer;
++++++if+(typeof+chunk+===+'string')+{
++++++++buffer+=+Buffer.from(chunk,+req.readableEncoding);
++++++}+else+{
++++++++buffer+=+chunk;
++++++}
++++++//+Handle+chunk
++});|code-block|syntax|javascript|3007492|当然，如果您从未调用过.setEncoding()，那么您就不必担心块会被作为string返回。|3007493|3007494|在你有了你的块作为Buffer之后，你就可以按照你的选择使用它了。考虑到完整性，这里介绍了如何使用预设的缓冲区大小，同时还检查了Content-Length|3007495|const+BUFFER_SIZE+=+4096;

/**
+*+@param+{IncomingMessage}+req
+*+@return+{Promise<Buffer>}
+*/
function+readEntireRequest(req)+{
++return+new+Promise((resolve,+reject)+=>+{
++++const+expectedSize+=+parseInt(req.headers['content-length'],+10)+%7C%7C+null;
++++let+data+=+Buffer.alloc(Math.min(BUFFER_SIZE,+expectedSize+%7C%7C+BUFFER_SIZE));
++++let+bytesWritten+=+0;
++++req.on('data',+(chunk)+=>+{
++++++if+((chunk.length+%2B+bytesWritten)+>+data.length)+{
++++++++//+Buffer+is+too+small.+Double+it.
++++++++let+newLength+=+data.length+*+2;
++++++++while+(newLength+<+chunk.length+%2B+data.length)+{
++++++++++newLength+*=+2;
++++++++}
++++++++const+newBuffer+=+Buffer.alloc(newLength);
++++++++data.copy(newBuffer);
++++++++data+=+newBuffer;
++++++}
++++++bytesWritten+%2B=+chunk.copy(data,+bytesWritten);
++++++if+(bytesWritten+===+expectedSize)+{
++++++++//+If+we+trust+Content-Length,+we+could+return+immediately+here.
++++++}
++++});
++++req.on('end',+()+=>+{
++++++if+(data.length+>+bytesWritten)+{
++++++++//+Return+a+slice+of+the+original+buffer
++++++++data+=+data.subarray(0,+bytesWritten);
++++++}
++++++resolve(data);
++++});
++++req.on('error',+(err)+=>+{
++++++reject(err);
++++});
++});
}|3007496|在这里使用缓冲区大小的选择是为了避免立即保留大量内存，而是只在需要时才获取RAM。Promise功能只是为了方便起见。|3007497|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/nodejs/node/blob/9949a2e1e3100c4ff1f228bac57c1af95cdc3e9d/lib/_stream_readable.js#L329|1|https://github.com/nodejs/node/blob/9949a2e1e3100c4ff1f228bac57c1af95cdc3e9d/deps/npm/node_modules/string_decoder/lib/string_decoder.js#L54^0|V|E|0|5|E|Q|D|1W|4|21|9|2N|5|2W|D|3E|M|47|M|19|F|0|4X|9|1|0|9|O|Y|M|1N|4|1Y|E|0|0|0|B|E|13|6|0|0|9|6|1S|E|0|0|15|7|0^^$0|@$1|2|3|4|5|6|7|19|8|@$9|1A|A|1B|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|1C|8|@$9|1D|A|1E|B|C]|$9|1F|A|1G|B|C]|$9|1H|A|1I|B|C]|$9|1J|A|1K|B|C]|$9|1L|A|1M|B|C]|$9|1N|A|1O|B|C]|$9|1P|A|1Q|B|C]|$9|1R|A|1S|B|C]]|D|@$9|1T|A|1U|1|1V]|$9|1W|A|1X|1|1Y]]|E|$]]|$1|H|3|I|5|6|7|1Z|8|@$9|20|A|21|B|C]|$9|22|A|23|B|C]|$9|24|A|25|B|C]|$9|26|A|27|B|C]]|D|@]|E|$]]|$1|J|3|K|5|6|7|28|8|@]|D|@]|E|$]]|$1|L|3|M|5|N|7|29|8|@]|D|@]|E|$O|P]]|$1|Q|3|R|5|6|7|2A|8|@$9|2B|A|2C|B|C]|$9|2D|A|2E|B|C]]|D|@]|E|$]]|$1|S|3|-4|5|6|7|2F|8|@]|D|@]|E|$]]|$1|T|3|U|5|6|7|2G|8|@$9|2H|A|2I|B|C]|$9|2J|A|2K|B|C]]|D|@]|E|$]]|$1|V|3|W|5|N|7|2L|8|@]|D|@]|E|$O|P]]|$1|X|3|Y|5|6|7|2M|8|@$9|2N|A|2O|B|C]]|D|@]|E|$]]|$1|Z|3|-4|5|6|7|2P|8|@]|D|@]|E|$]]]|10|$11|$5|12|13|14|E|$15|16]]|17|$5|12|13|14|E|$15|18]]]]

Everyone here is on the right track, but to put the bed the issue, you cannot call <code>.setEncoding()</code> EVER.

If you call <code>.setEncoding()</code>, it will create a <code>StringDecoder</code> and set it as the <a href="https://github.com/nodejs/node/blob/9949a2e1e3100c4ff1f228bac57c1af95cdc3e9d/lib/_stream_readable.js#L329" rel="nofollow noreferrer">default decoder</a>. If you try to pass <code>null</code> or <code>undefined</code>, then it will still create a <code>StringDecoder</code> with its default decoder of <code>UTF-8</code>. Even if you call <code>.setEncoding('binary')</code>, it's the same as calling <code>.setEncoding('latin1')</code>. Yes, <a href="https://github.com/nodejs/node/blob/9949a2e1e3100c4ff1f228bac57c1af95cdc3e9d/deps/npm/node_modules/string_decoder/lib/string_decoder.js#L54" rel="nofollow noreferrer">seriously</a>. 

I wish I could say you set <code>._readableState.encoding</code> and <code>_readableState.decoder</code> back to <code>null</code>, but when you call <code>.setEncoding()</code> buffer gets wiped and replaced with a binary encoding of the decoded string of what was there before. That means your data has already been changed.

If you want to "undo" the decoding, you have to re-encode the data stream back into binary like so:

<pre><code> req.on('data', (chunk) =&gt; {
 let buffer;
 if (typeof chunk === 'string') {
 buffer = Buffer.from(chunk, req.readableEncoding);
 } else {
 buffer = chunk;
 }
 // Handle chunk
 });
</code></pre>

Of course, if you never call <code>.setEncoding()</code>, then you don't have to worry about the chunk being returned as a <code>string</code>.

<hr>

After you have a your chunk as <code>Buffer</code>, then you can work with it as you chose. In the interested of thoroughness, here's how to use with a preset buffer size, while also checking <code>Content-Length</code>:

<pre><code>const BUFFER_SIZE = 4096;

/**
 * @param {IncomingMessage} req
 * @return {Promise&lt;Buffer&gt;}
 */
function readEntireRequest(req) {
 return new Promise((resolve, reject) =&gt; {
 const expectedSize = parseInt(req.headers['content-length'], 10) || null;
 let data = Buffer.alloc(Math.min(BUFFER_SIZE, expectedSize || BUFFER_SIZE));
 let bytesWritten = 0;
 req.on('data', (chunk) =&gt; {
 if ((chunk.length + bytesWritten) &gt; data.length) {
 // Buffer is too small. Double it.
 let newLength = data.length * 2;
 while (newLength &lt; chunk.length + data.length) {
 newLength *= 2;
 }
 const newBuffer = Buffer.alloc(newLength);
 data.copy(newBuffer);
 data = newBuffer;
 }
 bytesWritten += chunk.copy(data, bytesWritten);
 if (bytesWritten === expectedSize) {
 // If we trust Content-Length, we could return immediately here.
 }
 });
 req.on('end', () =&gt; {
 if (data.length &gt; bytesWritten) {
 // Return a slice of the original buffer
 data = data.subarray(0, bytesWritten);
 }
 resolve(data);
 });
 req.on('error', (err) =&gt; {
 reject(err);
 });
 });
}
</code></pre>

The choice to use a buffer size here is to avoid immediately reserving a large amount of memory, but instead only fetch RAM as needed. The <code>Promise</code> functionality is just for convenience.

I would like to retrieve binary data from an https request.

I found a similar question that uses the request method, 
<a href="https://stackoverflow.com/questions/14855015/getting-binary-content-in-node-js-using-request">Getting binary content in Node.js using request</a>, is says setting encoding to null should work, but it doesn't.

<pre><code>options = {
 hostname: urloptions.hostname,
 path: urloptions.path,
 method: 'GET',
 rejectUnauthorized: false,
 encoding: null
};

req = https.request(options, function(res) {
 var data;
 data = "";
 res.on('data', function(chunk) {
 return data += chunk;
 });
 res.on('end', function() {
 return loadFile(data);
 });
 res.on('error', function(err) {
 console.log("Error during HTTP request");
 console.log(err.message);
 });
})
</code></pre>

Edit: setting encoding to 'binary' doesn't work either

Getting binary content in node.js with http.request

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我想从https请求中检索二进制数据。我发现了一个使用请求方法的类似的问题，它说将编码设置为null应该有效，但它不起作用。options = {    hostname: urloptions.hostname,    path: urloptions.path,    method: 'GET',    rejec...

问使用http.request获取node.js中的二进制内容
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