Function isParameters

isParameters<T>(func): T extends ((...args: infer Arguments) => infer Output)
    ? Output extends Promise<infer R>
        ? ((...args: Arguments) => Promise<R | null>)
        : ((...args: Arguments) => Output | null)
    : never
Tests parameters.

Tests a function, by wrapping the function and checking its parameters through is function. If some parameter does not match the expected type, it returns null. Otherwise there's no type error, it returns the result of the function.

By the way, if you want is not just testing type checking, but also finding detailed type error reason(s), then use assertParameters or validateParameters instead.

On the other hand, if you don't want to allow any superfluous properties, utilize equalsParameters, assertEqualsParameters or validateEqualsParameters instead.
Type Parameters
- T extends ((...args: any[]) => any)
  Target function type
Parameters
- func: T
  Target function to test
Returns T extends ((...args: infer Arguments) => infer Output)
    ? Output extends Promise<infer R>
        ? ((...args: Arguments) => Promise<R | null>)
        : ((...args: Arguments) => Output | null)
    : never
The wrapper function with type tests

Author
Jeongho Nam - https://github.com/samchon
- Defined in src/functional.ts:405