JavaScript Program to Check Leap Year

Posted in JavaScript Tutorial

Updated on Oct 30, 2024

By Mari Selvan

👁️ 335 - Views

⏳ 4 mins

💬 1 Comment

Photo Credit to CodeToFun

🙋 Introduction

In the realm of programming, determining whether a given year is a leap year is a common requirement. A leap year is a year that is evenly divisible by 4, except for end-of-century years, which must be divisible by 400 to be a leap year. Checking for leap years involves implementing specific rules to validate the year.

In this tutorial, we will explore a JavaScript program designed to check whether a given year is a leap year.

📄 Example

Let's delve into the JavaScript code that accomplishes this task.

isLeapYear.js

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// Function to check if a year is a leap year
function isLeapYear(year) {
  // Leap year conditions
  if ((year % 4 === 0 && year % 100 !== 0) || (year % 400 === 0))
    return true; // True, it's a leap year
  else
    return false; // False, it's not a leap year
}

// Driver program
// Replace this value with the year you want to check
const year = 2024;

// Call the function to check if the year is a leap year
if (isLeapYear(year))
  console.log(`${year} is a leap year.`);
else
  console.log(`${year} is not a leap year.`);

💻 Testing the Program

To test the program with different years, modify the value of year in the code.

Output

2024 is a leap year.

🧠 How the Program Works

The program defines a function isLeapYear that takes an integer year as input and returns true if the year is a leap year, and false otherwise.
The function checks leap year conditions: the year must be divisible by 4 and not divisible by 100, or it must be divisible by 400.
Replace the value of year in the main program with the desired year you want to check.
The program calls the isLeapYear function and prints the result using console.log.

📏 Between the Given Range

Let's dive into the javascript code that checks for leap years in the specified range.

isLeapYear.js

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// Function to check if a year is a leap year
function isLeapYear(year) {
  return (year % 4 === 0 && year % 100 !== 0) || (year % 400 === 0);
}

// Function to find leap years in the range
function findLeapYearsInRange(startYear, endYear) {
  let leapYears = [];

  for (let year = startYear; year <= endYear; year++) {
    if (isLeapYear(year)) {
      leapYears.push(year);
    }
  }

  return leapYears;
}

// Driver program
const startYear = 2024;
const endYear = 2050;

// Call the function to find leap years in the range
const leapYearsInRange = findLeapYearsInRange(startYear, endYear);

// Output the result
console.log(`Leap Years in the range ${startYear} to ${endYear}:`);
console.log(leapYearsInRange.join(" "));

💻 Testing the Program

The provided code is already set to check for leap years in the range from 2024 to 2050.

Output

Leap years in the range 2024 to 2050:
2024 2028 2032 2036 2040 2044 2048

Run the script to see the leap years in the specified format.

🧠 How the Program Works

The program defines a function isLeapYear that checks if a given year is a leap year.
It then defines a function findLeapYearsInRange that iterates through the specified range and collects leap years.
The main section tests the program by specifying the range from 2024 to 2050 and outputs the result in the specified format.

🧐 Understanding the Concept of Leap Year

Before delving into the code, let's understand the concept of leap years. Leap years are years that are evenly divisible by 4, except for end-of-century years, which must be divisible by 400 to be a leap year.