pages shaking when viewer show and hide

why need these code?

 if (document.body.scrollHeight > document.body.clientHeight) {
          document.body.style.paddingRight = '15px';
}

I can't understand its meaning and it cause my page shaking.
Thank u for your help

I found that in windows computer, it works right. the problem is in my mac computer, the scrollbar doesn't take up any space。 it appears when scroll and hide when scroll finished. so the operation paddingRight = '15px' is unnecessary

[infeng]

Fixed in react-viewer@3.2.4 via #228. Body padding compensation is now applied only when the browser reports a positive layout scrollbar width, so overlay scrollbars no longer cause the page shift described here. The change includes regression coverage and Chromium verification.