Scheduler APILimited availability
The scheduler API provides a way to prioritize all tasks belonging to an application.
Not yet supported in all major browsers — check the table and provide a fallback.
Browser support
DesktopChrome
1–128Not supported
129+Supportedsince Sep 17, 2024
Current: 155Edge
12–128Not supported
129+Supportedsince Sep 19, 2024
Current: 154Firefox
1–141Not supported
142+Supportedsince Aug 19, 2025
Current: 157Safari
✕Not supportedup to 27
Current: 27MobileChrome Android
18–128Not supported
129+Supportedsince Sep 17, 2024
Current: 155Firefox Android
4–141Not supported
142+Supportedsince Aug 19, 2025
Current: 157Safari iOS
✕Not supportedup to 27
Current: 27How to use
Not supported in Safari, Safari iOS. Use feature detection below and provide a fallback (or a polyfill) for those browsers.
Example
Full syntax and examples are on MDN: Scheduler.
Feature detection
JS · check before using
if ("Scheduler" in globalThis) {
// Scheduler is available
} else {
// load a polyfill or use a fallback
}Sub-features
Support for each part of the feature (14). The overall table above shows when the whole feature works.
| Sub-feature | Chrome | Edge | Firefox | Safari | Chrome Android | Firefox Android | Safari iOS |
|---|---|---|---|---|---|---|---|
| Scheduler | 94 | 94 | 142 | ✕ | 94 | 142 | ✕ |
| Scheduler.postTask | 94 | 94 | 142 | ✕ | 94 | 142 | ✕ |
| Scheduler.yield | 129 | 129 | 142 | ✕ | 129 | 142 | ✕ |
| TaskController | 94 | 94 | 142 | ✕ | 94 | 142 | ✕ |
| TaskController.TaskController | 94 | 94 | 142 | ✕ | 94 | 142 | ✕ |
| TaskController.setPriority | 94 | 94 | 142 | ✕ | 94 | 142 | ✕ |
| TaskPriorityChangeEvent | 94 | 94 | 142 | ✕ | 94 | 142 | ✕ |
| TaskPriorityChangeEvent.TaskPriorityChangeEvent | 94 | 94 | 142 | ✕ | 94 | 142 | ✕ |
| TaskPriorityChangeEvent.previousPriority | 94 | 94 | 142 | ✕ | 94 | 142 | ✕ |
| TaskSignal | 94 | 94 | 142 | ✕ | 94 | 142 | ✕ |
| TaskSignal.any_static | 116 | 116 | 142 | ✕ | 116 | 142 | ✕ |
| TaskSignal.priority | 94 | 94 | 142 | ✕ | 94 | 142 | ✕ |
| TaskSignal.prioritychange_event | 94 | 94 | 142 | ✕ | 94 | 142 | ✕ |
| scheduler | 94 | 94 | 142 | ✕ | 94 | 142 | ✕ |