Scrollbar width detect

scrollbar-width-detect.js

var scrollBarWidth

window.getScrollBarWidth = function getScrollBarWidth() {
    if (scrollBarWidth !== undefined) {
        return scrollBarWidth
    }

    var scrollDetector = document.createElement('div')

    scrollDetector.style.width = '50px'
    scrollDetector.style.height = '50px'
    scrollDetector.style.overflow = 'visible'
    scrollDetector.style.position = 'absolute'
    scrollDetector.style.visibility = 'hidden'

    document.body.appendChild(scrollDetector)

    var widthWithoutScrollBar = scrollDetector.clientWidth

    scrollDetector.style.overflow = 'scroll'

    var widthWithScrollBar = scrollDetector.clientWidth

    document.body.removeChild(scrollDetector)

    return scrollBarWidth = widthWithoutScrollBar - widthWithScrollBar
}