area.y0()

area.y0([y])

If y is specified, sets the y0 accessor to the specified function or number and returns this area generator. If y is not specified, returns the current y0 accessor, which defaults to:

function y() {
  return 0;
}

When an area is generated, the y0 accessor will be invoked for each defined element in the input data array, being passed the element d, the index i, and the array data as three arguments. See area.x0 for more information.