JSFiddle - React, Tailwind, and code Playground

JavaScript

// Function to get doc width by measuring a 100% width div
var getDocWidth = function() {
    // Create div
    var e = jQuery('<div></div>');
    // Set width
    e.css({
        'position':'absolute',
        'top':'0',
        'left':'0',
        'width':'100%'
    })
    // Append to body
    jQuery('body').append(e);
    // Get width
    var w = e.innerWidth();
    // Remove
    e.remove();
    // Return
    return w;
};

// Add a div so scrollbars appear
var e = jQuery('<div>---</div>')
// Set its style
e.css({
    'position':'absolute',
    'top':'0',
    'left':'0',
    'height':(jQuery(document).height() + 20) + 'px'        
});
// Append it to the body
jQuery('body').append(e);
// Append details to the body
jQuery('body').append(
    '<p>Width:</p>' + 
    '<p>document object says: ' + jQuery(document).width() + 'px</p>' +
    '<p>element width 100% says: ' + getDocWidth() + 'px</p>'
);