re-thinking switch code

switch.js

function counter(state = 0, action) {
  switch (action.type) {
    case 'INCREMENT':
      return state + 1
    case 'DECREMENT':
      return state - 1
    default:
      return state
  }
}

//change to

const counter = (state = 0, action) =>
  action.type === 'INCREMENT'   ? state + 1
  : action.type === 'DECREMENT' ? state - 1
                                : state
                                
// change to

const switchcase = cases => defaultCase => key =>
  cases.hasOwnProperty(key) ? cases[key] : defaultCase
  
const counter = (state = 0, action) =>
  switchcase({
    'INCREMENT': state + 1,
    'DECREMENT': state -1
  })(state)(action.type)
  
// change to 

const switchcaseF = cases => defaultCase => key =>
  switchcase(cases)(defaultCase)(key)()
  
const counter = (state = 0, action) =>
  switchcaseF({
    'INCREMENT': () => state + 1,
    'DECREMENT': () => state -1
  })(() => state)(action.type)
  
// change to 
const executeIfFunction = f =>
  f instanceof Function ? f() : f
  
const switchcaseF = cases => defaultCase => key =>
  executeIfFunction(switchcase(cases)(defaultCase)(key))

const counter = (state = 0, action) =>
  switchcaseF({
    'INCREMENT': () => state + 1,
    'DECREMENT': () => state -1
  })(state)(action.type)
  
const counter = (state = 0, action) =>
  switchcaseF({
    'RESET': 0,
    'INCREMENT': () => state + 1,
    'DECREMENT': () => state -1
  })(state)(action.type)

var day;
switch (new Date().getDay()) {
    case 0:
        day = "Sunday";
        break;
    case 1:
        day = "Monday";
        break;
    case 2:
        day = "Tuesday";
        break;
    case 3:
        day = "Wednesday";
        break;
    case 4:
        day = "Thursday";
        break;
    case 5:
        day = "Friday";
        break;
    case 6:
        day = "Saturday";
}

then we can use this like:

const getDay = switchcase({
    0: 'Sunday',
    1: 'Monday',
    2: 'Tuesday',
    3: 'Wednesday',
    4: 'Thursday',
    5: 'Friday',
    6: 'Saturday'
  })('Unknown')
const getCurrentDay = () =>
  getDay(new Date().getDay())
const day = getCurrentDay()