To check if a year is a leap year in JavaScript, we can check if the year is evenly divisible by 4 and it isn’t evenly divisible by 100, or the year is evenly divisible by 400.
For instance, we can write:
const leapYear = (year) => {
return ((year % 4 === 0) && (year % 100 !== 0)) || (year % 400 === 0);
}
console.log(leapYear(1900))
console.log(leapYear(2016))
to create the leapYear function that does the checks.
We check if year is evenly divisible by 4 and it isn’t evenly divisible by 100 with:
(year % 4 === 0) && (year % 100 !== 0)
And we check if year is evenly divisible by 400 with:
year % 400 === 0
We join both expressions together with the OR operator.
Therefore, the first console log should log false since it’s evenly divisble by 4 but not evenly divisble by 100, and it’s not evenly divisible by 400.
On the other hand, the 2nd console log should log true , since it’s evenly divisible by 4 and it’s not evenly divisible by 100.
