JavaScript: Find the leap years from a given range of years

JavaScript Array: Exercise-16 with Solution

Find the leap years in a given range of years.

Visual Presentation:

Sample Solution:

JavaScript Code:

// Function to generate an array of leap years within a specified range
function leap_year_range(st_year, end_year) {
  // Initialize an array 'year_range' to store all years within the range
  var year_range = [];

  // Loop through the years in the specified range and add them to the array
  for (var i = st_year; i <= end_year; i++) {
    year_range.push(i);
  }

  // Initialize a new array 'new_array' to store leap years
  var new_array = [];

  // Use forEach to iterate through each year in 'year_range'
  year_range.forEach(
    function(year) {
      // Call the 'test_LeapYear' function to check if the current year is a leap year
      if (test_LeapYear(year)) {
        // If it is a leap year, add it to 'new_array'
        new_array.push(year);
      }
    }
  );

  // Return the array of leap years
  return new_array;
}

// Function to test if a given year is a leap year
function test_LeapYear(year) {
  // Check if the year is divisible by 4 but not divisible by 100, or if it is divisible by 100 and 400
  if ((year % 4 === 0 && year % 100 !== 0) || (year % 100 === 0 && year % 400 === 0)) {
    // Return the year if it's a leap year
    return year;
  } else {
    // Return false if it's not a leap year
    return false;
  }
}

// Output the array of leap years in the range 2000 to 2012
console.log(leap_year_range(2000, 2012));

Output:

[2000,2004,2008,2012]

Flowchart:

ES6 Version:

// Function to generate an array of leap years within a specified range
const leap_year_range = (st_year, end_year) => {
  // Initialize an array 'year_range' to store all years within the range
  const year_range = [];

  // Loop through the years in the specified range and add them to the array
  for (let i = st_year; i <= end_year; i++) {
    year_range.push(i);
  }

  // Initialize a new array 'new_array' to store leap years
  const new_array = [];

  // Use forEach to iterate through each year in 'year_range'
  year_range.forEach((year) => {
    // Call the 'test_LeapYear' function to check if the current year is a leap year
    if (test_LeapYear(year)) {
      // If it is a leap year, add it to 'new_array'
      new_array.push(year);
    }
  });

  // Return the array of leap years
  return new_array;
};

// Function to test if a given year is a leap year
const test_LeapYear = (year) => {
  // Check if the year is divisible by 4 but not divisible by 100, or if it is divisible by 100 and 400
  if ((year % 4 === 0 && year % 100 !== 0) || (year % 100 === 0 && year % 400 === 0)) {
    // Return the year if it's a leap year
    return year;
  } else {
    // Return false if it's not a leap year
    return false;
  }
};

// Output the array of leap years in the range 2000 to 2012
console.log(leap_year_range(2000, 2012));

Live Demo:

See the Pen JavaScript - Find the leap years from a given range of years - array-ex- 16 by w3resource (@w3resource) on CodePen.

Improve this sample solution and post your code through Disqus.

Previous: Write a JavaScript program to the colors entered in an array by a specific format.
Next: Write a JavaScript program to shuffle an array.