The CSSSkewY interface of the CSS Typed Object Model API represents the skewY() value of the individual transform property in CSS.
CSSSkewY
skewY()
MDN Reference
The ay property of the along the y-axis (or ordinate).
ay
The is2D read-only property of the CSSTransformComponent interface indicates where the transform is 2D or 3D.
is2D
The toMatrix() method of the object.
toMatrix()