300 - String to Number

[437204933]

// your answers
type StringNumber = '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9'

type IsNumber<S extends string> =  
  S extends `${infer First}${infer Rest}` 
    ? First extends (StringNumber | '.' )
      ? IsNumber<Rest> 
      : false
    : never


type StringNumberArray<S extends string, R extends 1[] = [], MAX = 1000> = 
`${R['length']}` extends S 
  ? R 
  : MAX extends R['length'] 
    ? [] 
    : StringNumberArray<S, [...R, 1]>

type GetInt<S> = S extends `${infer Int}.${infer Rest}` ? Int : S

type ToNumber<S extends string> = IsNumber<S> extends true ? StringNumberArray<GetInt<S>> extends any[] ? StringNumberArray<GetInt<S>>['length'] : never : never