GUIDE深度 · Deep dive
Are Browser Timers Accurate?
Browsers use setInterval for display, but the real timing comes from Date.now timestamps; returning from a background tab recalibrates, so throttling does not 'lose' time. Audio/vibration may still be throttled, so leave margin for critical reminders.
Store the end timestamp and subtract the current time.
Background throttling only affects refresh frequency.
Audio needs a user gesture.
System sleep may suspend the page.
FAQ
Does it lose time in the background?
No, it recalibrates by timestamp; the alert may be delayed.
Can it time a race?
Not recommended; use dedicated timing equipment.
Sources
Related calculators
Online TimerCountdown with 1-60 minute presets/custom, stopwatch laps and pause/reset; alarm with sound and vibration, all local.More guides
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