Determine one year from a date
Add one to the UTC year.
function plusOneYear(date) { const d = new Date(date); d.setUTCFullYear(d.getUTCFullYear() + 1); return d.toISOString().slice(0, 10); }Input & expected output
Input
"2026-10-28"Expected output
"2027-10-28"The edge case
Input
"2024-02-29"Expected output
"2025-03-01"Know the limits
- February 29 rolls over to March 1 in a non-leap year, as the edge case shows; clamp to February 28 if your contract requires it.
The function above is the implementation used by the lab. The lab validates JSON types and caps size before execution; include equivalent validation when accepting untrusted input in your application.
Source & maintenance
Based on Determine one year from now from the original 1loc collection by Nguyen Huu Phuoc. Copyright (c) 2020 phuoc-ng. MIT licensed.
Takes the date as an input and documents the February 29 rollover. Original MDX retained as inert source evidence.
Maintained by Oveyon. Original source commit: 14b481cf60df. This edition’s file: contents/determine-one-year-from-now.mdx in akamind/1loc, commit 0a77f131b22d. Read the license.
Keep exploring
- Compare two dates — Compare validated ISO calendar dates in UTC and return -1, 0 or 1.
- Add AM PM suffix to an hour — Turn an hour from 0 to 23 into a 12-hour label with am or pm.
- Calculate the number of days between two dates — Count whole calendar days between two YYYY-MM-DD dates.