fbz/src/util/dom.js

Fork of the OpenBazaar 2.0 browser-based client.

let scrollBarWidth = 0;

// https://gist.github.com/kflorence/3086552
export function getScrollBarWidth() {
  if (scrollBarWidth) return scrollBarWidth;

  const inner = document.createElement('p');
  inner.style.width = '100%';
  inner.style.height = '200px';

  const 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);
  const w1 = inner.offsetWidth;
  outer.style.overflow = 'scroll';
  let w2 = inner.offsetWidth;

  if (w1 === w2) {
    w2 = outer.clientWidth;
  }

  document.body.removeChild(outer);

  scrollBarWidth = w1 - w2;

  return scrollBarWidth;
}