Converting days into years months and weeks - JavaScript

We are required to write a JavaScript function that takes in a number (representing the number of days) and returns an object with four properties:

years, months, weeks, days

The properties should have proper values that can be made from the total number of days. We assume a standard year has 365 days and each month has 30 days for simplicity.

Problem Example

If the input is 738 days, the output should be:

{
  years: 2,
  months: 0,
  weeks: 1,
  days: 1
}

Solution Using Sequential Subtraction

The approach is to subtract the largest time unit first (years), then months, weeks, and finally remaining days:

const days = 738;

const calculateTiming = d => {
  let months = 0, years = 0, days = 0, weeks = 0;
  
  while(d){
    if(d >= 365){
      years++;
      d -= 365;
    }else if(d >= 30){
      months++;
      d -= 30;
    }else if(d >= 7){
      weeks++;
      d -= 7;
    }else{
      days++;
      d--;
    }
  };
  
  return {
    years, months, weeks, days
  };
};

console.log(calculateTiming(days));

{ years: 2, months: 0, weeks: 1, days: 1 }

Alternative Solution Using Division

A more efficient approach using mathematical division and remainder operations:

const calculateTimingOptimized = totalDays => {
  let remaining = totalDays;
  
  const years = Math.floor(remaining / 365);
  remaining = remaining % 365;
  
  const months = Math.floor(remaining / 30);
  remaining = remaining % 30;
  
  const weeks = Math.floor(remaining / 7);
  const days = remaining % 7;
  
  return { years, months, weeks, days };
};

// Test with different values
console.log(calculateTimingOptimized(738));  // 738 days
console.log(calculateTimingOptimized(400));  // 400 days
console.log(calculateTimingOptimized(50));   // 50 days

{ years: 2, months: 0, weeks: 1, days: 1 }
{ years: 1, months: 1, weeks: 0, days: 5 }
{ years: 0, months: 1, weeks: 2, days: 6 }

How It Works

The calculation follows this hierarchy:

• 1 year = 365 days
• 1 month = 30 days
• 1 week = 7 days
• Remaining = days

For 738 days: 738 ÷ 365 = 2 years (730 days), leaving 8 days. Then 8 ÷ 7 = 1 week (7 days), leaving 1 day.

Conclusion

Both approaches work effectively, but the mathematical division method is more efficient than the loop-based subtraction. Choose the division approach for better performance with large numbers.