Exercise 20: Check if Year is Leap Year
Problem Statement
Create a function `isLeapYear(year)` that checks if year is leap year.
Rules: Divisible by 4, but not by 100 unless also by 400.
Example:
- isLeapYear(2024) → true
- isLeapYear(1900) → false
Sample Output:
isLeapYear(2024) => true isLeapYear(1900) => false isLeapYear(2000) => true
Solution
const isLeapYear = (year) => {
const y = Number(year);
if (!Number.isInteger(y)) return false;
return (y % 4 === 0 && y % 100 !== 0) || (y % 400 === 0);
};Explanation
Overall Goal:
- Leap year check karna (february 29 days).
Line 1: Function header
const isLeapYear = (year) => {
Line 2: Convert
const y = Number(year);
Line 3: Validation
if (!Number.isInteger(y)) return false;
Line 4: Leap year logic
return (y % 4 === 0 && y % 100 !== 0) || (y % 400 === 0);- Divisible by 4, but not 100, unless also 400.
Real world:
- Date calculations: calendar apps.
- Form validation: date validation.
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