The SVGAnimatedAngle interface is used for attributes of basic type \ which can be animated.
SVGAnimatedAngle
MDN Reference
The animVal read-only property of the SVGAnimatedAngle interface represents the current animated value of the associated <angle> on an SVG element.
animVal
<angle>
The baseVal read-only property of the SVGAnimatedAngle interface represents the base (non-animated) value of the associated <angle> on an SVG element.
baseVal