StGewehr

Hi @OSUblake !
 
My thanks for quick response. Actually, I was very close, I just split declaration and addition of a method to prototype into different files, and it works fine.
So it should look something like this (perhaps for those who find this topic).
 
//some index.ts /// <reference path="./utils/extensions/gsap.d.ts"/> import "./utils/extensions/gsap.extensions"; //gsap.d.ts declare namespace gsap.core { export interface Timeline { deepKill(): void; } } //gsap.extensions.ts import { gsap } from "gsap"; gsap.core.Timeline.prototype.deepKill = function () { this.getChildren(true, true, true).forEach((animation) => animation.kill()); this.kill(); };  
Thanks,
Yury