three.js/src/extras/ShapeUtils.d.ts

interface Vec2 {
	x: number;
	y: number;
}

export namespace ShapeUtils {
	export function area( contour: Vec2[] ): number;
	export function triangulate( contour: Vec2[], indices: boolean ): number[];
	export function triangulateShape( contour: Vec2[], holes: Vec2[] ): number[][];
	export function isClockWise( pts: Vec2[] ): boolean;
}