How can I get the browser's scrollbar sizes?

From Alexandre Gomes Blog I have not tried it. Let me know if it works for you.

function getScrollBarWidth () {
  var inner = document.createElement('p');
  inner.style.width = "100%";
  inner.style.height = "200px";

  var 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);
  var w1 = inner.offsetWidth;
  outer.style.overflow = 'scroll';
  var w2 = inner.offsetWidth;
  if (w1 == w2) w2 = outer.clientWidth;

  document.body.removeChild (outer);

  return (w1 - w2);
};

This is only script I've found, which is working in webkit browsers ... :)

$.scrollbarWidth = function() {
  var parent, child, width;

  if(width===undefined) {
    parent = $('<div style="width:50px;height:50px;overflow:auto"><div/></div>').appendTo('body');
    child=parent.children();
    width=child.innerWidth()-child.height(99).innerWidth();
    parent.remove();
  }

 return width;
};

Minimized version:

$.scrollbarWidth=function(){var a,b,c;if(c===undefined){a=$('<div style="width:50px;height:50px;overflow:auto"><div/></div>').appendTo('body');b=a.children();c=b.innerWidth()-b.height(99).innerWidth();a.remove()}return c};

And you have to call it when document is ready ... so

$(function(){ console.log($.scrollbarWidth()); });

Tested 2012-03-28 on Windows 7 in latest FF, Chrome, IE & Safari and 100% working.

source: http://benalman.com/projects/jquery-misc-plugins/#scrollbarwidth

window.scrollBarWidth = function() {
  document.body.style.overflow = 'hidden'; 
  var width = document.body.clientWidth;
  document.body.style.overflow = 'scroll'; 
  width -= document.body.clientWidth; 
  if(!width) width = document.body.offsetWidth - document.body.clientWidth;
  document.body.style.overflow = ''; 
  return width; 
} 

This should do the trick, no?

function getScrollbarWidth() {
  return (window.innerWidth - document.documentElement.clientWidth);
}

function getScrollBarWidth() {
    return window.innerWidth - document.documentElement.clientWidth;
}

Most of the browser use 15px for the scrollbar width

function getWindowScrollBarHeight() {
    let bodyStyle = window.getComputedStyle(document.body);
    let fullHeight = document.body.scrollHeight;
    let contentsHeight = document.body.getBoundingClientRect().height;
    let marginTop = parseInt(bodyStyle.getPropertyValue('margin-top'), 10);
    let marginBottom = parseInt(bodyStyle.getPropertyValue('margin-bottom'), 10);
    return fullHeight - contentHeight - marginTop - marginBottom;
  }

Here's the more concise and easy to read solution based on offset width difference:

function getScrollbarWidth(): number {

  // Creating invisible container
  const outer = document.createElement('div');
  outer.style.visibility = 'hidden';
  outer.style.overflow = 'scroll'; // forcing scrollbar to appear
  outer.style.msOverflowStyle = 'scrollbar'; // needed for WinJS apps
  document.body.appendChild(outer);

  // Creating inner element and placing it in the container
  const inner = document.createElement('div');
  outer.appendChild(inner);

  // Calculating difference between container's full width and the child width
  const scrollbarWidth = (outer.offsetWidth - inner.offsetWidth);

  // Removing temporary elements from the DOM
  outer.parentNode.removeChild(outer);

  return scrollbarWidth;

}

See the JSFiddle.

Already coded in my library so here it is:

var vScrollWidth = window.screen.width - window.document.documentElement.clientWidth;

I should mention that jQuery $(window).width() can also be used instead of window.document.documentElement.clientWidth.

It doesn't work if you open developer tools in firefox on the right but it overcomes it if the devs window is opened at bottom!

window.screen is supported quirksmode.org!

Have fun!

It seems to work, but maybe there is a simpler solution that works in all browsers?

// Create the measurement node
var scrollDiv = document.createElement("div");
scrollDiv.className = "scrollbar-measure";
document.body.appendChild(scrollDiv);

// Get the scrollbar width
var scrollbarWidth = scrollDiv.offsetWidth - scrollDiv.clientWidth;
console.info(scrollbarWidth); // Mac:  15

// Delete the DIV 
document.body.removeChild(scrollDiv);

.scrollbar-measure {
 width: 100px;
 height: 100px;
 overflow: scroll;
 position: absolute;
 top: -9999px;
}

I made an updated version of @Matthew Vines answer.

It's easier to read, easier to understand. It doesn't require an inner element. The element created to get the scroll bar width has a 100% height/width so it doesn't create any visible scroll bar on the body on lower end PCs/mobiles which could take a bit more time to create the element, get the widths, and finally remove the element.

const getScrollBarWidth = () => {
  const e = document.createElement('div');
  Object.assign(e.style, {
    width: '100%',
    height: '100%',
    overflow: 'scroll',
    position: 'absolute',
    visibility: 'hidden',
    top: '0',
    left: '0',
  });

  document.body.appendChild(e);

  const scrollbarWidth = e.offsetWidth - e.clientWidth;

  document.body.removeChild(e);

  return scrollbarWidth;
};

console.log(getScrollBarWidth());

I do recommend to check for the scroll bar width only once, at page load (except if it doesn't fit your needs) then store the result in a state/variable.

I've found that solution in the material-ui code and it works for me.

const scrollbarWidth = window.innerWidth -  document.querySelector('body').clientWidth;

You can use this solution to find the scrollbar width of any element inside the webpage rather than the webpage itself. You can also rewrite it to work for scrollbar height in the case of horizontal scrolbars by replacing its width related properties with their height related counterparts.

The offsetWidth property returns the total width of content, padding, border, and scrollbar (if there is any). Whereas, clientWidth property returns only the total width of content and padding.

So, if we substract clientWidth and horizontal border from offsetWidth, we will be left with the width of the scrollbar. That is to say, if there is any scrollbar, we will get the width of the scrollbar. But if there isn't any scrollbar, we will get 0.

const element = document.querySelector("div");
const elementStyle = window.getComputedStyle(element);
const horizontalBorder = parseFloat(elementStyle.borderLeftWidth) + parseFloat(elementStyle.borderRightWidth);
const scrollbarWidth = element.offsetWidth - element.clientWidth - horizontalBorder + "px";