Date.prototype.setUTCDate() changes the day of the month for this date according to universal time (UTC) (MDN). It mutates the Date in place and returns the new timestamp.
date.setUTCDate(dateValue)
dateValue: typically 1 … 31 (UTC day)
→ returns new timestamp (ms)
→ mutates date
setUTCDate(19) // set UTC day to 19
setUTCDate(32) // overflow → next month
setUTCDate(0) // last day of previous monthCall date.setUTCDate. Start with this line.
date.setUTCDate(day)| Call | What it does |
|---|---|
date.setUTCDate(day) | Primary signature. |
date.setUTCDate(...) | Call with the arguments your case needs. |
Built into JavaScript. Call setUTCDate(...) on a Date instance — no import required.
date.setUTCDate(day)| Parameter | Description |
|---|---|
| dateValue | Required. UTC day of month (1–31 typical; overflow OK) |
| Return Value | Description |
|---|---|
| * | New epoch ms (number), not the Date |
MDN: read the UTC day, then change it with setUTCDate().
const event = new Date("August 19, 1975 23:15:30 GMT-3:00");
console.log(event.getUTCDate()); // 20
event.setUTCDate(19);
console.log(event.getUTCDate()); // 19GMT-3:00 shifts the instant so UTC day is 20.getUTCDate() reports 20.setUTCDate(19) sets the UTC calendar day to 19.event now reads day 19.Values past the end of the month normalize forward (MDN).
const d = new Date(Date.UTC(2026, 0, 31)); // Jan 31, 2026 UTC
d.setUTCDate(32);
console.log(d.getUTCMonth()); // 1 (February)
console.log(d.getUTCDate()); // 1
console.log(d.toISOString()); // "2026-02-01T00:00:00.000Z"1, day 1.setUTCDate(0) → Last Day of Previous MonthDay 0 counts back into the previous UTC month (MDN).
const d = new Date(Date.UTC(2026, 0, 15)); // Jan 15, 2026 UTC
d.setUTCDate(0);
console.log(d.toISOString()); // "2025-12-31T00:00:00.000Z"
console.log(d.getUTCDate()); // 310. That means “day before the 1st” of the current month.Date.prototype.setUTCDate() is part of the language from early ECMAScript and is Baseline Widely available (MDN).
Supported in every modern browser and Node.js. No polyfill needed for ordinary web apps.
Bottom line: Safe everywhere. Focus on mutation, month overflow, and UTC vs local choice.
Learn how to set the UTC year, and optionally month and day, on a Date.
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