getFullYear()
ES1+Returns the year of the specified date according to local time.
Syntax
date.getFullYear()Return Value
A number representing the year
Examples
const date = new Date('2024-01-15');
console.log(date.getFullYear());📌 When to Use
Use getFullYear() for copyright notices, age calculations, year-based filtering, or any display requiring the full 4-digit year.
⚠️ Common Mistakes
Using the deprecated getYear() method instead of getFullYear() - getYear() returns years since 1900.
Forgetting that getFullYear() uses local time, which may differ from the server time zone.
✅ Best Practices
Always use getFullYear() instead of getYear() for Y2K-safe code.
For UTC year, use getUTCFullYear() to avoid timezone-related issues.
⚡ Performance Notes
getFullYear() is a simple property extraction with O(1) complexity. There is no performance concern even when called frequently.
🌍 Real World Example
Age Calculator
Calculate exact age from birth date, accounting for whether birthday has occurred this year.
function calculateAge(birthDate) {
const today = new Date();
const birth = new Date(birthDate);
let age = today.getFullYear() - birth.getFullYear();
const monthDiff = today.getMonth() - birth.getMonth();
// Adjust if birthday hasn't occurred yet this year
if (monthDiff < 0 || (monthDiff === 0 && today.getDate() < birth.getDate())) {
age--;
}
return {
age,
birthYear: birth.getFullYear(),
nextBirthday: `${birth.getMonth() + 1}/${birth.getDate()}`
};
}
console.log(calculateAge('1990-06-15'));
// { age: 33, birthYear: 1990, nextBirthday: '6/15' }