src/utils/getScrollBarWidth.js
export default () => {
let inner = document.createElement('p')
inner.style.width = '100%'
inner.style.height = '200px'
let 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)
let w1 = inner.offsetWidth
outer.style.overflow = 'scroll'
let w2 = inner.offsetWidth
if (w1 === w2) w2 = outer.clientWidth
document.body.removeChild(outer)
return (w1 - w2)
}