Type alias Properties<T>

Properties<T>: {
    [K in Keys<T>]-?: ExcludeNullable<T[K]> extends AnyFunction
        ? never
        : K
}[Keys<T>]

Get the literal names of keys that are propeties, basically anything that's not a method in object type T

Properties<{
     barBaz: string;
     bazBar: Numeric;
     bar: () => number; 
   }> // Result: 'barBaz' | 'bazBar'