Higher order reducer for default case

defaultReducerCase.js

function createReducerWithDefaultCase(decl, initial) {
  const defaultCase = decl['*'];
  delete decl['*'];
  const reducer = createReducer(decl, initital);

  if (!defaultCase) return reducer;
  
  const declaredActions = Object.keys(decl);

  return (state, action) => {
    if (declaredActions.includes(action.type)) {
      return reducer(state,action);
    }
    
    return defaultCase(state, action.payload);
  };
}

createReducerWithDefaultCase({
  [increment]: state => state + 1,
  [decrement]: state => state - 1,
  '*': () => 0,
}, 0);