Navigator 3.0
image.width
The width property of the Image object is a read-only integer that specifies the width of image. It is set by the WIDTH attribute of the <IMG> HTML tag.
The WIDTH attribute is optional in HTML, but including it greatly improves the layout time of your pages. Also, because of a bug, in Navigator 2.0 all images in a page that contains JavaScript must have WIDTH and HEIGHT attributes specified (even though the Image object is not available in 2.0).