How to get bytes of string in node.js?

Question

I want to read the size of bytes of a file as I read it. I have this

var path = 'training_data/dat1.txt';

var fs = require("fs"); //Load the filesystem module
var stats = fs.statSync(path);
var fileSizeInBytes = stats["size"];

var accSize = 0;

var lineReader = require('readline').createInterface({
    input: fs.createReadStream(path)
});
lineReader.on('line', function (line) {
    accSize += Buffer.byteLength(line, 'utf8');
    console.log(accSize + "/" + fileSizeInBytes);
});
lineReader.on('close', function() {
    console.log('completed!');
});

But it doesn't print out the correct filesize.

it prints this for example.

Does anyone know whats wrong?

NanoWizard · Accepted Answer · 2015-12-27 02:35:31Z

2

The lineReader doesn't include the newline \n character in the buffer as each line is read, which is where your bytes are missing.

Try this:

accSize += Buffer.byteLength(line + '\n', 'utf8');

EDIT

If the file being read uses Windows line endings, you'll need to add two characters, since those will also have a carriage return in addition to line feed, denoted as '\r\n'. (see this for more details)

edited Dec 27, 2015 at 2:35

answered Dec 27, 2015 at 0:05

NanoWizard

2,1641 gold badge24 silver badges35 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

omega Over a year ago

It worked when I did + '\\n' (its actually 3 more characters for some reason), and then since the last line doesn't have a new line character, I just added 2 to the total size, and then in the end, it printed 168/168.

NanoWizard Over a year ago

'\n' is actually a single character. By adding an additional '\', you are escaping the other '\', so instead of newline, you're using the literal string '\n'. In any case, if you needed to add two characters, it's probably because your document is formatted with windows line endings, which include a carriage return ('\r\n'). I'll add that to my answer

Collectives™ on Stack Overflow

How to get bytes of string in node.js?

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related