function getDocHeight() {
    var D = document;
    return Math.max(
        Math.max(D.body.scrollHeight, D.documentElement.scrollHeight),
        Math.max(D.body.offsetHeight, D.documentElement.offsetHeight),
        Math.max(D.body.clientHeight, D.documentElement.clientHeight)
    );
}
//alert(getDocHeight())
document.write('<img src="tall_lines.png" alt="lines" height="')
document.write(getDocHeight())
document.write('px" width="9px" />')