The code below assumes that we use arguments in regular JavaScript. Well, we don’t, we use the same rest parameter syntax you do in TypeScript. Actually, because you are writing TypeScript, and because of the support for rest params operator is not yet 100%, behind the scenes you might use arguments, too, in your compiled code.

I like your article and I like TypeScript but please stop using antiquated JS techniques and make comparisons with TS. Use the latest features of the language, put that code through Babel, and you’ll realize that TypeScript has nothing more than type annotations and interfaces, over JavaScript — I’m simplifying a lot but it’s only to highlight that there aren’t that many differences between JS and TS.