JavaScript Date getMilliseconds() Method

What You’ll Learn

getMilliseconds() returns the millisecond fraction within the current second as an integer from 0 to 999 in local time. This guide covers syntax, five examples, comparisons with getTime(), validation, and formatting patterns.

Introduction

Timestamps, logs, and animations sometimes need sub-second precision. The getMilliseconds() method reads the millisecond part of a Date object—the value after the decimal point inside the current second.

Do not confuse it with getTime(), which returns the full milliseconds since January 1, 1970 UTC. For elapsed duration between two moments, subtract getTime() values or use Date.now().

Understanding the getMilliseconds() Method

Date.prototype.getMilliseconds() is a zero-argument instance method. It never mutates the original Date—it only reads the millisecond component (0–999) within the current second in local time.

Think of a clock showing 14:30:45.250. getSeconds() returns 45 and getMilliseconds() returns 250—not the entire timestamp as one number.

📝 Syntax

dateObj.getMilliseconds()

Parameters

• None.

Return value

• Integer 0–999 for a valid date in local time.
• NaN if dateObj is an invalid Date.

Examples Gallery

Open DevTools Console (F12) or use Try-it links. Fixed times use new Date(y, m, d, h, min, sec, ms) for predictable local values.

const now = new Date();
const ms = now.getMilliseconds();

console.log("Milliseconds:", ms);

Milliseconds: 342

const stamp = new Date(2026, 6, 4, 14, 30, 45, 250);

console.log(stamp.getSeconds());       // 45
console.log(stamp.getMilliseconds());  // 250

45
250

function safeGetMilliseconds(date) {
  if (!(date instanceof Date) || Number.isNaN(date.getTime())) {
    return null;
  }
  return date.getMilliseconds();
}

console.log(safeGetMilliseconds(new Date()));              // e.g. 512
console.log(safeGetMilliseconds(new Date("not-a-date")));  // null

512
null

function formatSecondsWithMs(date) {
  const sec = date.getSeconds();
  const ms = String(date.getMilliseconds()).padStart(3, "0");
  return sec + "." + ms + "s";
}

console.log(formatSecondsWithMs(new Date(2026, 6, 4, 14, 30, 7, 5)));
// "7.005s"

7.005s

const start = Date.now();

// Simulate work
let sum = 0;
for (let i = 0; i < 100000; i++) {
  sum += i;
}

const elapsed = Date.now() - start;
console.log("Elapsed:", elapsed, "ms");

Elapsed: 2 ms

🚀 Common Use Cases

• Log timestamps — append .ms fractions to second-level logs.
• UI clocks — show tenths or milliseconds in a stopwatch display.
• Event ordering — break ties when two events share the same second.
• Testing — assert sub-second fields on constructed dates.
• Media sync — align cues within a second boundary.
• Debugging — inspect the exact ms slot on a parsed date.

📝 Notes

• getMilliseconds() is local; use getUTCMilliseconds() for UTC.
• Range is 0–999 only—not total epoch milliseconds.
• For elapsed duration, use getTime() or Date.now().
• Invalid dates propagate NaN—validate first.
• Pad with padStart(3, "0") when displaying fixed-width fractions.
• For high-precision benchmarks, consider performance.now() in browsers.

💡 Best Practices