get_image_url_dimensions.js

var fs = require('fs'),
		request = require('request'),
		sizeOf = require('image-size');

var url = "http://www.dailytechtuts.com/wp-content/uploads/cute-white-rat.jpg";
var file_path = '/tmp/google.png'

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(url, file_path, function(){
  console.log('done');  
	sizeOf(file_path, function (err, dimensions) {
	  console.log(dimensions.width, dimensions.height);
	 	fs.unlink(file_path);
	});
});