I am writing a program in TypeScript and compiling code to JavaScript before running it on a browser. This is my package.json scripts:

"scripts": {
  "clean": "rm -rf dist/",
  // gsap.min.js is under ts/src/lib/
  "build": "tsc && copyfiles -u 1 ts/src/lib/* dist/"
},

However, I cannot reference gsap in a TypeScript file as I get the the error Cannot find name 'gsap'. I believe this is because tsc does not read minified files (even if allowJs flag is true).

I can, however, use gsap fine in a JavaScript file, since the checking is less strict. (In JavaScript, referencing a variable that is not defined only throws an error when run, e.g. in browser console.)

Attempt to fix

I tried defining gsap, hoping gsap.min.js will then override the variable. However, gsap remains undefined at runtime (at least tsc compiles this with no errors). So this does not work.

<!-- index.html snippet -->
<script src="dist/src/lib/pseudo.js"></script>
<script src="dist/src/lib/gsap.min.js"></script>

// pseudo.js
let gsap: any;