Proposal: is.create(URLSearchParams)

[szmarczak]

const isSearchParams = is.create(URLSearchParams);

is.any([is.string, isSearchParams]);

[sindresorhus]

Can you describe how exactly it should behave? Because you're passing in the constructor, which would mean you want a instanceof check internally, but that's not a good or portable way to check.

[szmarczak]

that's not a good or portable way to check.

Is there a better choice? We could compare the names but that's not good either - e.g. there are many FormData implementations but they differ.

The create function returns another function. But it can have an extra feature: if used with any it will display that class name: E.g. Expected string or URLSearchParams instance, got ...

[sindresorhus]

Pass in a string and use

is/source/index.ts

Line 100 in 238e8c8

const isObjectOfType = <T>(type: ObjectTypeName) => (value: unknown): value is T => getObjectType(value) === type;

That's how most of the testing is done here.

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Yes, we could read the name from the passed in constructor. I just fear that it will make people assume it does instance checking, which it does not.