node.js readSync and stream return different results

Asked Mar 06 '18 at 07:43

Active Mar 06 '18 at 07:43

Viewed 184 times

I want to read file with stream to update UI progress bar. But after I start experimenting with fs.createReadStream I noticed that I receive different results. For example:

var d = fs.readFileSync('file.bin', null);
console.log(d);
console.log(d.byteLength);

Returns in console:

Buffer(188000)

188000

But this code:

var rd = fs.createReadStream('file.bin');
var data = '';
rd.on("error", function(err) {
    console.log(err);
});
rd.on("data", function(chunk) {
    console.log(chunk.length);
    data += chunk;
});
rd.on("end", function() {
    console.log('There will be no more data.');
    var buf = Buffer.from(data, null);
    console.log(buf)
    console.log(buf.byteLength)
});

Returns in console:

Uint8Array(297684)

297684

Why stream returns Uint8Array instead of Buffer object and why they have different sizes

asked Mar 06 '18 at 07:43

Arti

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Both `fs.createReadStream()` and `Buffer.from()` allow you to specify the desired encoding. – jfriend00 Mar 06 '18 at 08:06
Worth reading this https://nodejs.org/api/buffer.html#buffer_buffers_and_typedarray about buffers and Uint8Array. A Uint8Array is a Buffer. – jfriend00 Mar 06 '18 at 08:10
I the same result from each approach in Windows using Node.js v6.9.2. Both return a length of 188000 (from a binary file of length 188000). – Terry Lennox Mar 06 '18 at 08:37
@jfriend00 I need raw data – Arti Mar 06 '18 at 09:30
@jfriend00 but why it creates not Buffer class... – Arti Mar 06 '18 at 09:39
Did you read that link? It is a Buffer object and can be used exactly like a Buffer object. – jfriend00 Mar 06 '18 at 16:23

node.js readSync and stream return different results

0 Answers0