Is it Leap Year? ....Using Javascript.

• Download LeapYear.zip - 0.4 KB

Introduction

A leap year is a year with one extra day inserted into February, the leap year is 366 days with 29 days in February as opposed to the normal 28 days.

Leap Year

In the Gregorian calendar, which is the calendar used by most modern countries, the following rules decide which years are leap years:

1. Every year divisible by 4 is a leap year.
2. But every year divisible by 100 is NOT a leap year
3. Unless the year is also divisible by 400, then it is still a leap year.

This means that year 1800, 1900, 2100, 2200, 2300 and 2500 are NOT leap years, while year 2000 and 2400 are leap years.

This actually means year 2000 is kind of special, as it is the first time the third rule is used in many parts of the world.

In the old Julian Calendar, there was only one rule: Every year divisible by 4 is a leap year. This calendar was used before the Gregorian calendar was adopted.

Here is I'm going to check the given year is leap or not...How to do....check it out..

I don't state that this code is perfect but it does work.

Using the code

Just copy and paste the following function in to script tag inside the header tag so that it can be called from anywhere in this HTML document.

function isleap()
{
 var yr=document.getElementById("year").value;
 if ((parseInt(yr)%4) == 0)
 {
  if (parseInt(yr)%100 == 0)
  {
    if (parseInt(yr)%400 != 0)
    {
    alert("Not Leap");
    return "false";
    }
    if (parseInt(yr)%400 == 0)
    {
    alert("Leap");
    return "true";
    }
  }
  if (parseInt(yr)%100 != 0)
  {
    alert("Leap");
    return "true";
  }
 }
 if ((parseInt(yr)%4) != 0)
 {
    alert("Not Leap");
    return "false";
 } 
}

Basically this code gives the rules to check if a year is a leap year. If the year is no divisible by 4 then it is not a leap year. If the year is divisible by 100 but not by 400 then it is not a leap year. Otherwise the remaining options leave us with a leap year so I hard coded what to do. The Reason I have coded in what to do otherwise is to highlight the two different statements of verifying that something does match and verifying something does not match.

Just call this script function where you want...as follows,

onclick="isleap()"