[WIP] Simple Time Difference Kata done by students: https://www.codewars.com/kata/simple-time-difference/train/javascript

time.js

// https://www.codewars.com/kata/simple-time-difference/train/javascript

function solve(arr){
  return arr.map(convertTimeToMinutes).sort((a, b) => a - b);
//   const day = convertTimeToMinutes('24:00')
//   const firstTime = convertTimeToMinutes(arr[0])
//   const nextDayTime = firstTime + day
//   return convertMinutesToTime(nextDayTime - firstTime - 1)
}

function calculateDistances(element, index, array) {
  const next = array[index + 1]
  const prev = array[index - 1]
  const current = element
  return next - current
}

function convertTimeToMinutes(timeString) {
  const hoursAndMins = timeString.split(':').map((elem) => parseInt(elem));
  const minutes = hoursAndMins[0] * 60 + hoursAndMins[1];
  return minutes
}

function convertMinutesToTime(totalMinutes) {
  const hours = Math.floor(totalMinutes / 60)
  const minutes = totalMinutes - hours * 60
  
  const format = (number) => number < 10 ? `0${number}` : `${number}`
  
  return format(hours) + ':' + format(minutes)
}

//////////

describe("Basic tests", function(){
  Test.assertEquals(solve(["14:51"]), "23:59");
  Test.assertEquals(solve(["23:00","04:22","18:05","06:24"]),"11:40");
  // Test.assertEquals(solve(["21:14", "15:34", "14:51", "06:25", "15:30"]),"09:10");
});

describe("time to integer converter", function(){
  Test.assertEquals(convertTimeToMinutes("01:10"), 70);
  Test.assertEquals(convertTimeToMinutes("00:00"), 0);
});

describe("integer to time converter", function(){
  Test.assertEquals(convertMinutesToTime(70), "01:10");
  Test.assertEquals(convertMinutesToTime(0), "00:00");
});

describe("calculate distances", function(){
  Test.assertEquals(calculateDistances(['00:10','01:15']), 65);
});