d3.polygonArea() method returns the signed area of the specified polygon. If the vertices of the polygon are in counterclockwise order (assuming a coordinate system where the origin ⟨0,0⟩ is in the top-left corner), the returned area is positive; otherwise it is negative, or zero.var d = [
[-1, 415.44],
[146.93, 304.47],
[195.45, 152.13],
[-1, 134.64]
];
var area = d3.polygonArea(d);
console.log(area) // Output: 36157.2759