Comment by nnx

The listed "Idle Detection" is a different spec that is way more invasive than requestIdleCallback (which seems on track to be deployed more generally in Safari).

It's about detecting user idleness, including in the case the user has another tab active, not a way to queue and coalesce bits of work at an "idle" moment to optimise for latency and battery life.

The Idle Detection spec at https://github.com/WICG/idle-detection says it itself:

"As opposed to the requestIdleCallback, this is not about asynchronously scheduling work when the system is idle."