Check if the given year is a leap year

Use new Date(), setting the date to February 29th of the given year. Use Date.prototype.getMonth() to check if the month is equal to 1.

const isLeapYear = year => new Date(year, 1, 29).getMonth() === 1;

// Examples
isLeapYear(2019); // false
isLeapYear(2020); // true

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