TaskSignal: prioritychange 事件

addEventListener("prioritychange", (event) => {});

onprioritychange = (event) => {};

<textarea id="log" style="min-height: 70px; width: 95%"></textarea>

let log = document.getElementById("log");
function mylog(text) {
  log.textContent += `${text}\n`;
}

if ("scheduler" in this) {
  // Declare a TaskController, setting its signal priority to 'user-blocking'
  const controller = new TaskController({ priority: "user-blocking" });

  // Listen for 'prioritychange' events on the controller's signal.
  controller.signal.addEventListener("prioritychange", (event) => {
    const previousPriority = event.previousPriority;
    const newPriority = event.target.priority;
    mylog(`Priority changed from ${previousPriority} to ${newPriority}.`);
  });

  // Post task using the controller's signal.
  // The signal priority sets the initial priority of the task
  scheduler.postTask(
    () => {
      mylog("Task 1");
    },
    { signal: controller.signal },
  );

  // Change the priority to 'background' using the controller
  controller.setPriority("background");
}