In this code I stream a file from a url and save it to a file. Is there a way to also pipe it through something that will count the number of bytes piped? (Which would tell me the file size.)

  request.stream(url)
    .pipe(outputFile)

Is there some library that would do this by piping the download through it, or a simple way for me to do it myself?

In this code I stream a file from a url and save it to a file. Is there a way to also pipe it through something that will count the number of bytes piped? (Which would tell me the file size.)

  request.stream(url)
    .pipe(outputFile)

Is there some library that would do this by piping the download through it, or a simple way for me to do it myself?

• javascript
• node.js
• download
• stream

2 Answers 2

You can do it like this with request library:

const request = require('request');
const fs = require('fs');

var downloaded = 0;
request.get(url)
  .on('data', function(chunk){
    downloaded += chunk.length;
    console.log('downloaded', downloaded);
  })
  .pipe(fs.createWriteStream(fileName));

Also, you can check this link to learn how to do it without request package.

Update #1 (Pure NodeJS solution)

var http = require('http');
var fs = require('fs');

var download = function(url, dest, cb) {
  var file = fs.createWriteStream(dest);
  var downloaded = 0;
  var request = http.get(url, function(response) {
    response.pipe(file);
    response.on('data', function(chunk){
      downloaded += chunk.length;
      console.log(downloaded);
    })
    file.on('finish', function() {
      file.close(cb);
    });
  });
}

With typings and byteLength property:

const stream: ReadStream = file.createReadStream(); 
const chunks: Buffer[] = [];
let fileSize = 0;

stream.on('data', (chunk: Buffer) => {
  fileSize += chunk.byteLength;

  chunks.push(chunk);
});

stream.once('end', () => {
  const fileBuffer = Buffer.concat(chunks);

  console.log('equal values:', fileBuffer.byteLength === fileSize);
});