coderef

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: 155
Edge
12–128Not supported
129+Supportedsince Sep 19, 2024
Current: 154
Firefox
1–141Not supported
142+Supportedsince Aug 19, 2025
Current: 157
Safari
✕Not supportedup to 27
Current: 27
MobileChrome Android
18–128Not supported
129+Supportedsince Sep 17, 2024
Current: 155
Firefox Android
4–141Not supported
142+Supportedsince Aug 19, 2025
Current: 157
Safari iOS
✕Not supportedup to 27
Current: 27

How 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-featureChromeEdgeFirefoxSafariChrome AndroidFirefox AndroidSafari iOS
Scheduler9494142✕94142✕
Scheduler.postTask9494142✕94142✕
Scheduler.yield129129142✕129142✕
TaskController9494142✕94142✕
TaskController.TaskController9494142✕94142✕
TaskController.setPriority9494142✕94142✕
TaskPriorityChangeEvent9494142✕94142✕
TaskPriorityChangeEvent.TaskPriorityChangeEvent9494142✕94142✕
TaskPriorityChangeEvent.previousPriority9494142✕94142✕
TaskSignal9494142✕94142✕
TaskSignal.any_static116116142✕116142✕
TaskSignal.priority9494142✕94142✕
TaskSignal.prioritychange_event9494142✕94142✕
scheduler9494142✕94142✕