cpt-waffle-lotide/dist/calculateDayInYear.ts

LoTide in Typescript

const DAYS_IN_MONTH:number[] = [31, 0, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];

const validMonth = (month:number):boolean => month >= 1 && month <= 12;

const validDay = (month:number, day:number):boolean => {
	return day >= 1 && day <= DAYS_IN_MONTH[month - 1];
}

const calculateDayNumber = (month:number, day:number):number => {
  let dayOfYear = day;
  for (let i = 1; i < month; i++) {
    dayOfYear += DAYS_IN_MONTH[i - 1];
  }
  return dayOfYear;
}

const isMultiple = (numerator:number, denominator:number):boolean => {
  return numerator % denominator === 0;
}

const isLeapYear = (year:number) => {
  const isMultipleFour:boolean         = isMultiple(year, 4);
  const isMultipleOneHundred:boolean   = isMultiple(year, 100);
  const isMultipleFourHundred:boolean  = isMultiple(year, 400);

  if (!isMultipleFour) {
  return false;
  } else if (isMultipleFour && !isMultipleOneHundred) {
    return true;
	} else {
    if (isMultipleOneHundred && !isMultipleFourHundred) {
      return false;
    } else {
      return true;
    }
  }
}


const calculateDayInYear = (date:string) => {
  const splitDate = date.split('/');
  const [year, month, day] = splitDate.map((val:string) => Number(val));
  DAYS_IN_MONTH[1] = isLeapYear(year) ? 29 : 28;
  if (validMonth(month) && validDay(month, day)) {
  	const result = calculateDayNumber(month, day);
    console.log(date, "is day", result, "of the year", year);
    return result;
  } else {
    console.log("Invalid date");
    return -1;
  }
}

export default calculateDayInYear;

/*
    Below are some simple tests!
    They run the function with a predetermined parameter and compare the output to the value we are expecting to get!
    The console.log will output either 'true' or 'false' based on whether or not the function
    returns a value that matched our expected value.
    You'll know your code works correctly when all of these tests return 'true'.
*/
// console.log("Tests:");
// console.log("---------------");
// console.log(calculateDayInYear("1900/3/2") === 61);
// console.log(calculateDayInYear("2000/3/2") === 62);
// console.log(calculateDayInYear("2012/2/29") === 60);
// console.log(calculateDayInYear("2015/12/31") === 365);