JavaScript: Get the amount of days of a year

JavaScript Datetime: Exercise-14 with Solution

Days in Year

Write a JavaScript function to get the number of days in a year.

Test Data :
console.log(days_of_a_year(2015));
365
console.log(days_of_a_year(2016));
366

Sample Solution:

JavaScript Code:

// Define a JavaScript function called days_of_a_year with parameter year
function days_of_a_year(year) 
{
   // Return 366 if the given year is a leap year, otherwise return 365
  return isLeapYear(year) ? 366 : 365;
}

// Define a JavaScript function called isLeapYear with parameter year
function isLeapYear(year) {
    // Return true if the given year is divisible by 400 or divisible by 4 but not divisible by 100
     return year % 400 === 0 || (year % 100 !== 0 && year % 4 === 0);
}

// Output the number of days in the year 2015
console.log(days_of_a_year(2015));
// Output the number of days in the year 2016
console.log(days_of_a_year(2016));

Output:

365
366

Explanation:

In the exercise above,

• The code defines a JavaScript function named "days_of_a_year()" with one parameter 'year', which represents the year for which we want to calculate the number of days.
• Inside the "days_of_a_year()" function:
• It returns the result of calling the "isLeapYear()" function with the given year.
• If the given year is a leap year (as determined by the "isLeapYear()" function), it returns 366, indicating that the year has 366 days.
• If the given year is not a leap year, it returns 365, indicating that the year has 365 days.
• The "isLeapYear()" function checks whether a given year is a leap year.
• It returns 'true' if the year is divisible by 400 or if the year is divisible by 4 but not divisible by 100, indicating that it's a leap year.
• Otherwise, it returns 'false'.

Flowchart:

Live Demo:

See the Pen JavaScript - Get the amount of days of a year-date-ex- 14 by w3resource (@w3resource) on CodePen.

For more Practice: Solve these Related Problems:

• Write a JavaScript function that determines if a given year is a leap year and returns 366 or 365 accordingly.
• Write a JavaScript function that calculates the number of days in a year by comparing January 1st of the year to January 1st of the next year.
• Write a JavaScript function that accepts a year and uses leap year logic to compute the correct number of days.
• Write a JavaScript function that validates the input year and handles non-numeric values gracefully.

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