Responsive image map coords

responsive_imagemap.js

// @mrdoob: Can't believe image maps aren't responsive

window.onload = function () {

	var image = document.getElementById( 'image' );
	var delta = image.clientWidth / 1024;

	var map = document.getElementById( 'map' );
	var areas = map.getElementsByTagName( 'area' );

	for ( var i = 0; i < areas.length; i ++ ) {

		var area = areas[ i ];
		var coords = area.coords.split( ',' );

		for ( var j = 0; j < coords.length; j ++ ) {

			coords[ j ] *= delta;

		}

		area.coords = coords.join( ',' );

	}

}