อ่านความกว้างของ scrollbar
<script type="text/javascript">
function getScrollBarWidth ()
{
var inner = document.createElement( 'p' );
inner.style.width = "100%";
inner.style.height = "200px";
var outer = document.createElement( 'div' );
outer.style.position = "absolute";
outer.style.top = "0px";
outer.style.left = "0px";
outer.style.visibility = "hidden";
outer.style.width = "200px";
outer.style.height = "150px";
outer.style.overflow = "hidden";
outer.appendChild (inner);
document.body.appendChild( outer );
var w1 = inner.offsetWidth;
outer.style.overflow = 'scroll';
var w2 = inner.offsetWidth;
if ( w1 == w2 ) w2 = outer.clientWidth;
document.body.removeChild( outer );
return ( w1 - w2 );
};
document.write( 'ความกว้างของ scrollbar คือ ' + getScrollBarWidth() + 'px' );
</script>
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