Tools
Chronometer
The chronometer is a browser-based stopwatch with lap recording capability. It measures elapsed time with millisecond precision using the browser's high-resolution performance API. Laps can be recorded at any point and reviewed as a list, making it useful for timing tests, deployments, or any sequential task.
What is the Chronometer?
The chronometer tool is a straightforward, high-precision stopwatch running entirely in the browser. It tracks elapsed time from the moment you press Start and allows you to record lap times without stopping the main timer. All timing is performed using the Web Performance API, which provides sub-millisecond resolution. The chronometer is useful for any scenario where you need to time a process without reaching for a physical device.
How does it work?
When you click Start, the tool records the current high-resolution timestamp. On each display update, the difference between now and the start time is computed and rendered as HH:MM:SS.mmm. Clicking Lap saves the current elapsed time to a list while the timer keeps running. Stop freezes the display, and Reset clears all values and laps. The timer runs independently of frame rate, so display lag does not affect measurement accuracy.
Typical Use Cases
- Timing the duration of a deployment or build process
- Recording lap times during manual performance testing
- Tracking time spent on individual steps in a runbook
- Simple everyday stopwatch tasks without installing an app
Step-by-step Guide
- Step 1: Click Start to begin timing.
- Step 2: Click Lap to record the current time without stopping.
- Step 3: Click Stop to pause the timer.
- Step 4: Click Reset to clear the timer and all recorded laps.
Tips & Notes
- Use the Lap function to record individual step durations during a multi-step process.
- Keep the browser tab active for the most accurate display refresh rate.
- Combine with the benchmark tool for structured JavaScript performance comparisons.
Frequently Asked Questions
How accurate is the chronometer?
The timer uses the browser's Performance.now() API, which provides sub-millisecond precision. Display updates are tied to requestAnimationFrame and may lag by up to one frame, but recorded timestamps are accurate.
Does the timer continue running when the tab is in the background?
Yes. The elapsed time calculation is based on wall-clock timestamps, not on display update cycles, so background tabs do not affect accuracy.
Chronometer
Stopwatch with lap time recording — measure the duration of operations, capture lap times, and export results.
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