d3.curveStepBefore(context)

area.y([y]) If y is specified, sets y0

curve.areaStart() Indicates the start of a new area segment. Each area segment consists of exactly two

arc.cornerRadius([radius]) If radius is specified, sets the corner radius to the specified function or number

radialArea(data) Equivalent to area.

area.curve([curve]) If curve is specified, sets the curve

radialLine.context([context]) Equivalent to

catmullRom.alpha(alpha) Returns a cubic Catmull–Rom curve with the specified alpha in the range [0, 1]. If

line.curve([curve]) If curve is specified, sets the curve

bundle.beta(beta) Returns a bundle curve with the specified beta in the range [0, 1], representing the bundle