element-react-codish/src/scrollbar/scrollbar-width.js

Element UI for React

let scrollBarWidth;

export function getScrollBarWidth() {
  if (scrollBarWidth !== undefined) return scrollBarWidth;

  const outer = document.createElement('div');
  outer.className = 'el-scrollbar__wrap';
  outer.style.visibility = 'hidden';
  outer.style.width = '100px';
  outer.style.position = 'absolute';
  outer.style.top = '-9999px';
  document.body.appendChild(outer);

  const widthNoScroll = outer.offsetWidth;
  outer.style.overflow = 'scroll';

  const inner = document.createElement('div');
  inner.style.width = '100%';
  outer.appendChild(inner);

  const widthWithScroll = inner.offsetWidth;
  scrollBarWidth = widthNoScroll - widthWithScroll;
  outer.parentNode.removeChild(outer);

  return scrollBarWidth;
}