scheduling-polyfill.d.ts

export type TaskPriority = "user-blocking" | "user-visible" | "background";

export type SchedulerPostTaskOptions = {
  // This priority is immutable and overrides the
  // TaskController's priority.
  priority?: TaskPriority;
  delay?: number;
  signal?: TaskSignal;
};

export type Scheduler = {
  postTask: <T>(
    task: () => Promise<T> | T,
    options?: SchedulerPostTaskOptions
  ) => Promise<T>;
};

export type TaskControllerInit = {
  // defaults to "user-visible"
  priority?: TaskPriority;
};

declare global {
  interface TaskController extends AbortController {
    readonly signal: TaskSignal;
    abort(): void;
    setPriority: (priority: TaskPriority) => void;
  }

  interface TaskSignal extends AbortSignal {
    readonly aborted: boolean;
    readonly priority: TaskPriority;
    addEventListener(
      event: "prioritychange" | "abort",
      handler: (event: Event) => void
    ): void;
  }

  let TaskController: {
    prototype: TaskController;
    new (init?: TaskControllerInit): TaskController;
  };

  let TaskSignal: {
    prototype: TaskSignal;
    new (): TaskSignal;
  };

  let scheduler: Scheduler;

  interface Window {
    scheduler: Scheduler;
    TaskController: typeof TaskController;
    TaskSignal: typeof TaskSignal;
  }
}