KITFORMA · EDITORIAL ANSWER
Why does setInterval not run exactly on schedule?
KitForma editorial guide. Timers schedule callbacks for a future opportunity; they do not reserve CPU at an exact wall-clock instant. Event-loop load and callback duration introduce delay.
Step-by-step answer
Timers schedule callbacks for a future opportunity; they do not reserve CPU at an exact wall-clock instant. Event-loop load and callback duration introduce delay.
Measure actual elapsed time with a monotonic clock and choose whether missed ticks should be skipped or caught up. For nonoverlapping asynchronous work, schedule the next run after the previous one completes instead of blindly starting another interval callback. Test a job that takes longer than its nominal interval. Timers inside one process are not durable scheduling; restart, sleep and deployment require a separate persistence policy if every run matters.
Sources and verification
Sources checked:
Scope: This editorial guide is based on the cited sources and tool behavior. A forum question or a query observed for our site does not establish market search volume, low competition, guaranteed rankings or inadequate answers elsewhere.
This editorial answer was prepared by KitForma with AI assistance. It is not presented as a real member question or an independent user review. Check the sources and the result with your own file; report corrections in the discussion.