three.js/examples/jsm/utils/BufferGeometryUtils.d.ts

import { BufferAttribute, BufferGeometry } from '../../../src/Three';

export namespace BufferGeometryUtils {
	export function mergeBufferGeometries( geometries: BufferGeometry[], useGroups?: boolean ): BufferGeometry;
	export function computeTangents( geometry: BufferGeometry ): null;
	export function mergeBufferAttributes( attributes: BufferAttribute[] ): BufferAttribute;
}