Strong Typed Switch Functional

example.ts

const getTwoColIndexByHorizontalRendering = switchCase<string, number | null>({
  '2 Column - 1 Column': 0,
  '1 Column - 2 Column': 1,
})(null);

// Examples
getTwoColIndexByHorizontalRendering('2 Column - 1 Column'); // returns 0
getTwoColIndexByHorizontalRendering('1 Column - 2 Column'); // returns 1
getTwoColIndexByHorizontalRendering('unknown layout');      // returns null

switch.ts

const executeIfFunction = <T>(f: T | (() => T)): T =>
  typeof f === 'function' ? (f as () => T)() : f;

const switchf =
  <ValueType>(cases: { [key: PropertyKey]: ValueType }) =>
  (defaultCase: ValueType) =>
  (key: PropertyKey) =>
    cases.hasOwnProperty(key) ? cases[key] : defaultCase;

export const switchCase =
  <KeyType extends PropertyKey, ValueType>(
    cases: { [key in KeyType]: ValueType }
  ) =>
  (defaultCase: ValueType) =>
  (key: KeyType) =>
    executeIfFunction<ValueType>(
      switchf<ValueType>(cases)(defaultCase)(key)
    );