wikimedia/mediawiki-extensions-Wikibase

( function () {
/**
 * Utility function retrieving the width of the browser's scrollbar.
 *
 * @member jQuery.util
 * @method getscrollbarwidth
 * @license GNU GPL v2+
 * @author H. Snater < mediawiki@snater.com >
 *
 * @return {number} Scrollbar width in pixel.
 */
    var getscrollbarwidth = ( function () {
        'use strict';

        var scrollbarWidth;

        return function () {
            if ( scrollbarWidth ) {
                return scrollbarWidth;
            }

            var $inner = $( '<p>' ).attr( 'style', 'width:100px;height:100px' ),
                $outer = $( '<div>' ).attr( 'style',
                    'position:absolute;top:-1000px;left:-1000px;visibility:hidden;'
                    + 'width:50px;height:50px;overflow:hidden;'
                ).append( $inner ).appendTo( $( 'body' ) ),
                widthWithoutScrollbar = $outer.get( 0 ).clientWidth,
                widthWithScrollbar;

            $outer.css( 'overflow', 'scroll' );

            widthWithScrollbar = $outer.get( 0 ).clientWidth;

            $outer.remove();

            scrollbarWidth = widthWithoutScrollbar - widthWithScrollbar;

            return scrollbarWidth;
        };

    }() );

    module.exports = getscrollbarwidth;

}() );