area.x0()

area.x0([x])

If x is specified, sets the x0 accessor to the specified function or number and returns this area generator. If x is not specified, returns the current x0 accessor, which defaults to:

function x(d) {
  return d[0];
}

When an area is generated, the x0 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. The default x0 accessor assumes that the input data are two-element arrays of numbers. If your data are in a different format, or if you wish to transform the data before rendering, then you should specify a custom accessor. For example, if x is a time scale and y is a linear scale:

var data = [
  {date: new Date(2007, 3, 24), value: 93.24},
  {date: new Date(2007, 3, 25), value: 95.35},
  {date: new Date(2007, 3, 26), value: 98.84},
  {date: new Date(2007, 3, 27), value: 99.92},
  {date: new Date(2007, 3, 30), value: 99.80},
  {date: new Date(2007, 4,  1), value: 99.47},
  …
];

var area = d3.area()
    .x(function(d) { return x(d.date); })
    .y1(function(d) { return y(d.value); })
    .y0(y(0));