Feature request: provide a function to calculate the area of a (multi)polygon

[Peque]

In example:

const polygonClipping = require('polygon-clipping')

const polygon = [[[0,0],[2,0],[0,2],[0,0]]]
polygonClipping.area(polygon) == 2
const multi = [[[[0,0],[2,0],[0,2],[0,0]]], [[[2,2],[4,2],[2,4],[2,2]]]]
polygonClipping.area(multi) == 4

[rowanwins]

There are many other libraries already available which do this, for example @turf/area does it with geojson data or 2d-polygon-area.

[Dylan190774]

I'd like to see this too.
The 2d-polygon-area library is very old and doesn't work well with ES6 and Typescript.

I also can't figure out how to calculate the different parts of MultiPolygon, since the rings (holes) should not be counted of course.