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NegativeNumber

A type that checks whether a given number type is negative. Returns never if it is not a negative number.


Interface​

typescript
type NegativeNumber<T extends number> = `${T}` extends `-${number}`
  ? T
  : never;

Usage​

Valid Negative Number Case​

typescript
import { NegativeNumber } from '@modern-kit/types';

type ValidNegativeNumber1 = NegativeNumber<-1>; // -1
type ValidNegativeNumber2 = NegativeNumber<-10>; // -10

Invalid Case​

typescript
import { NegativeNumber } from '@modern-kit/types';

type InvalidNegativeNumber1 = NegativeNumber<1>;   // never
type InvalidNegativeNumber2 = NegativeNumber<0>;   // never
type InvalidNegativeNumber3 = NegativeNumber<1.5>; // never