Jonathan Ong Jonathan Ong - 1 month ago 15
Node.js Question

Downloading images with node.js

I'm trying to write a script to download images using node.js. This is what I have so far:

var maxLength = 10 // 10mb
var download = function(uri, callback) {
http.request(uri)
.on('response', function(res) {
if (res.headers['content-length'] > maxLength*1024*1024) {
callback(new Error('Image too large.'))
} else if (!~[200, 304].indexOf(res.statusCode)) {
callback(new Error('Received an invalid status code.'))
} else if (!res.headers['content-type'].match(/image/)) {
callback(new Error('Not an image.'))
} else {
var body = ''
res.setEncoding('binary')
res
.on('error', function(err) {
callback(err)
})
.on('data', function(chunk) {
body += chunk
})
.on('end', function() {
// What about Windows?!
var path = '/tmp/' + Math.random().toString().split('.').pop()
fs.writeFile(path, body, 'binary', function(err) {
callback(err, path)
})
})
}
})
.on('error', function(err) {
callback(err)
})
.end();
}


I, however, want to make this more robust:


  1. Are there libraries that do this and do this better?

  2. Is there a chance that response headers lie (about length, about content type)?

  3. Are there any other status codes I should care about? Should I bother with redirects?

  4. I think I read somewhere that
    binary
    encoding is going to be deprecated. What do I do then?

  5. How can I get this to work on windows?

  6. Any other ways you can make this script better?



Why: for a feature similar to imgur where users can give me a URL, I download that image, and rehost the image in multiple sizes.

Answer

I'd suggest using the request module. Downloading a file is as simple as the following code:

var fs = require('fs'),
    request = require('request');

var download = function(uri, filename, callback){
  request.head(uri, function(err, res, body){
    console.log('content-type:', res.headers['content-type']);
    console.log('content-length:', res.headers['content-length']);

    request(uri).pipe(fs.createWriteStream(filename)).on('close', callback);
  });
};

download('https://www.google.com/images/srpr/logo3w.png', 'google.png', function(){
  console.log('done');
});