Typescript Parameters get types for methods that allow either one or two arguments e.g. Element.scrollBy

Issue

For example, how can I get the options parameter of scrollBy() method?

Parameters<Element["scrollTo"]>

only returns [x: number, y: number] and not options?: ScrollToOptions

scrollTo(options?: ScrollToOptions): void;
scrollTo(x: number, y: number): void;

Solution

Please see this issue and TS docs:

When inferring from a type with multiple call signatures (such as the type of an overloaded function), inferences are made from the last signature (which, presumably, is the most permissive catch-all case). It is not possible to perform overload resolution based on a list of argument types.

Parameters always returns last call signature

In this case it worth using :

const foo:Element["scrollTo"]=(...args:unknown[])=>{

}

Answered By - captain-yossarian