get an image's dimensions using pure js

gistfile1.txt

/**
* get an image's dimensions using pure js
*/
var img = new Image();
img.onload = function() {
    document.write('<strong>image:</strong> ' + this.src + '<br><strong>width:</strong> '+ this.width + '<br><strong>Height:</strong> ' + this.height);
}
img.src = 'http://domain.com/image.jpg';