A recent tweet by Dan Loewenherz, Co-Founder and CTO at Champify, posed a JavaScript pop quiz, asking developers to identify the return value of new Date().getYear(). The question highlights a long-standing "gotcha" in JavaScript's date handling, where the getYear() method does not return the four-digit year as intuitively expected, but rather the year minus 1900.
"JavaScript pop quiz! What does this return? new Date().getYear()," stated Dan Loewenherz in his tweet.
This behavior stems from early JavaScript implementations and the lead-up to the Year 2000 (Y2K) problem, where many systems struggled with two-digit year representations. For instance, if the current year is 2025, getYear() would return 125 (2025 - 1900). For years between 1900 and 1999, it returned a two-digit value (e.g., 99 for 1999).
The getYear() method has been officially deprecated in JavaScript for many years due to its inconsistent and non-standard behavior across different browser versions and its lack of Y2K compliance. Developers are strongly advised to avoid its use in modern code.
The recommended and standard alternative for retrieving the full four-digit year is getFullYear(). This method consistently returns the complete year, such as 2025, ensuring accurate date calculations and avoiding the historical pitfalls associated with getYear().
The continued presence of getYear() in the language serves primarily for backward compatibility with legacy systems.
Dan Loewenherz, a seasoned software engineer with a background from Yale University and previous roles at companies like Heap and The Black Tux, frequently engages with the developer community on technical nuances. His quiz serves as a reminder for both new and experienced developers about the importance of understanding deprecated features and adopting current best practices in JavaScript programming.