Date.prototype.setHours() changes the hour (and optionally minutes, seconds, milliseconds) of a date in local time. It mutates the Date in place and returns the new timestamp.
date.setHours(hours)
date.setHours(hours, minutes)
date.setHours(hours, minutes, seconds)
date.setHours(hours, minutes, seconds, ms)
hours: 0 … 23 (local)
→ returns new timestamp (ms)
→ mutates date
setHours(20) // keep minutes/seconds
setHours(20, 21, 22) // set H:M:S togetherCall date.setHours. Start with this line.
date.setHours(h[, min[, sec[, ms]]])| Call | What it does |
|---|---|
date.setHours(h[, min[, sec[, ms]]]) | Primary signature. |
date.setHours(...) | Call with the arguments your case needs. |
Built into JavaScript. Call setHours(...) on a Date instance — no import required.
date.setHours(h[, min[, sec[, ms]]])| Parameter | Description |
|---|---|
| hoursValue | Required. Local hour (typically 0–23; overflow allowed) |
| minutesValue | Optional. Local minutes (0–59); keep current if omitted |
| secondsValue / msValue | Optional. Must provide earlier parts if you pass these |
| Return Value | Description |
|---|---|
| * | The value returned by date.setHours(). |
Change the hour and keep the existing minutes and seconds.
const event = new Date(1975, 7, 19, 23, 15, 30);
event.setHours(20);
console.log(event.getHours()); // 20
console.log(event.getMinutes()); // 157 is August.setHours(20). Only the hour argument is provided.15.event now reads hour 20.Pass multiple arguments to snap to an exact local time of day.
const event = new Date(1975, 7, 19, 23, 15, 30);
event.setHours(20, 21, 22);
console.log(event.getHours()); // 20
console.log(event.getMinutes()); // 21
console.log(event.getSeconds()); // 22setHours(20, 21, 22) sets hour, minute, and second.Values outside 0–23 normalize into later calendar days.
const d = new Date(2026, 2, 15, 10, 0, 0); // Mar 15, 2026 10:00
d.setHours(25);
console.log(d.getDate()); // 16
console.log(d.getHours()); // 110.1.Date.prototype.setHours() has been in JavaScript since ES1. It is Baseline and works in every modern browser and Node.js — no polyfill needed.
Supported everywhere Date exists: Chrome, Firefox, Safari, Edge, Internet Explorer, and all Node.js versions.
Bottom line: Safe to use in any environment. Watch mutation and DST when adjusting local hours. See also the MDN setHours() reference.
Learn how to set the milliseconds portion of a Date in local time.
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