Why setTimeout is Inaccurate? ❌

setTimeout and setInterval in JavaScript are based on the event loop and task queue. Their execution time may vary due to several factors:

Event Loop Mechanism:

JavaScript executes code within a single event loop. If earlier tasks take a long time or the task queue is busy, the timer callback will be delayed.

Task Queue Priority:

The priority of tasks in the task queue varies. User interaction events or rendering updates might have higher priority than setTimeout and setInterval, delaying their execution.

JavaScript Engine Limitations:

The JS engine normally imposes a minimum delay; for example, nested setTimeout calls usually have a minimum delay of 4 milliseconds.

System Performance and Load:

System performance and current load can also affect timer accuracy. High system load can further delay task execution.

What setTimeout Really Does in Angular
In JavaScript, setTimeout queues a task on the macrotask queue to be run after the current call stack clears. In a normal JS app, this is predictable.

But Angular isn’t just JavaScript — it uses Zone.js under the hood.

Zone.js monkey-patches setTimeout so Angular can trigger change detection after async operations.

Every time setTimeout fires, Angular knows something changed. So it runs its entire component tree check cycle.