The width of this rectangle.
This is equivalent to the width function in jQuery and the calculated
width CSS value, converted to a dimensionless num in pixels. Unlike
getBoundingClientRect, width will return the same numerical width if
the element is hidden or not.
Set the current computed width in pixels of this element.
newWidth can be either a num representing the width in pixels or a
Dimension object. This is equivalent to the width function in jQuery
and the calculated
width CSS value, converted to a dimensionless num in pixels.
Note that only the content width can be set via this method.