Snippet to determine scrollbar width

gistfile1.js

/**
 * Simple function to determine scrollbar width.
 * Extracted from JqueryUI source and changed to get rid
 * of jQuery dependency.
 */
function getScrollBarWidth() {
    var w1, w2,
        div = document.createElement('div'),
        inner = document.createElement('div');                
        
    div.style = { position: 'absolute', width: '50px', height: '50px', overflow: 'hidden' };
    inner.style = { height: '100px' };
    
    div.appendChild(inner);
    document.body.append(div);
    
    w1 = inner.offsetWidth;
    div.style.overflow = 'scroll';
    w2 = inner.offsetWidth;
    if ( w1 === w2 ) w2 = div.clientWidth;
    
    div.parentNode.removeChild(div);
    
    return w1 - w2;
}