Scheduler

{{APIRef("Prioritized Task Scheduling API")}}{{AvailableInWorkers}}

The Scheduler interface of the Prioritized Task Scheduling API provides methods for scheduling prioritized tasks.

A Scheduler can be accessed from the global object using {{domxref("Window.scheduler")}} or {{domxref("WorkerGlobalScope.scheduler")}} within a worker.

Instance properties

None.

Instance methods

• {{domxref('Scheduler.postTask()')}}
  • : Adds a task to the scheduler as a callback, optionally specifying a priority, delay, and/or a signal for aborting the task.
• {{domxref('Scheduler.yield()')}}
  • : Yields control of the main thread back to the browser, returning a promise that resolves to continue execution where it left off.

Examples

If the feature is defined, an instance of this object is returned by the {{jsxref("globalThis")}} property in both workers and the main thread.

The code below shows a simple task that resolves with the text 'Task executing'. This text is logged on success. The code also shows a catch block, which would be required in more complex code to handle when a task is aborted or throws an error.

if ("scheduler" in this) {
  // Post task with default priority: 'user-visible' (no other options)
  // When the task resolves, Promise.then() logs the result.
  scheduler
    .postTask(() => "Task executing")
    .then((taskResult) => console.log(`${taskResult}`)) // Log result
    .catch((error) => console.error(`Error: ${error}`)); // Log errors
}

For more comprehensive example code see Prioritized Task Scheduling API > Examples.

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}