conveyal/modeify

var outer = document.createElement('div');
outer.style.visibility = 'hidden';
outer.style.width = '100px';
outer.style.msOverflowStyle = 'scrollbar'; // needed for WinJS apps

document.body.appendChild(outer);

var widthNoScroll = outer.offsetWidth;
// force scrollbars
outer.style.overflow = 'scroll';

// add innerdiv
var inner = document.createElement('div');
inner.style.width = '100%';
outer.appendChild(inner);

var widthWithScroll = inner.offsetWidth;

// remove divs
outer.parentNode.removeChild(outer);

module.exports = widthNoScroll - widthWithScroll;