The Element.clientWidth property is zero for inline elements and elements with no CSS; otherwise, it's the inner width of an element in pixels. It includes padding but excludes borders, margins, and vertical scrollbars (if present).
When clientWidth is used on the root element (the <html> element), (or on <body> if the document is in quirks mode), the viewport's width (excluding any scrollbar) is returned. This is a special case of clientWidth.
Note: This property will round the value to an integer. If you need a fractional value, use element.getBoundingClientRect().
