signal

Access the task's internal AbortSignal.

Syntax

task.signal: AbortSignal

Return Value

The internal AbortSignal that is aborted when the task is cancelled.

Description

The signal property provides read-only access to the task's internal AbortSignal. This signal is aborted when cancel() is called on the task, and all executions created by run() will listen to this signal.

Examples

Check Cancellation State

const task = FuturableTask.of(() => longOperation());

console.log(task.signal.aborted); // false
task.cancel();
console.log(task.signal.aborted); // true

Listen to Abort Event

const task = FuturableTask.of(() => operation());

task.signal.addEventListener('abort', () => {
  console.log('Task was cancelled');
});

task.cancel(); // Logs: "Task was cancelled"

Pass to Native APIs

const task = FuturableTask.of(() => {
  // Pass signal to fetch
  return fetch('/api/data', { signal: task.signal });
});

Manual Polling with Signal

const task = new FuturableTask((resolve, reject, { signal }) => {
  const interval = setInterval(() => {
    if (signal.aborted) {
      clearInterval(interval);
      reject(new Error('Cancelled'));
      return;
    }

    checkStatus().then(status => {
      if (status === 'ready') {
        clearInterval(interval);
        resolve(status);
      }
    });
  }, 1000);
});

Coordinating Cancellation

const parentTask = FuturableTask.of(() => mainOperation());

// Child task inherits parent's signal
const childTask = new FuturableTask(
  (resolve) => {
    resolve(childOperation());
  },
  parentTask.signal // Use parent's signal
);

// Cancelling parent cancels child
parentTask.cancel();
console.log(childTask.signal.aborted); // true

Use Cases

Resource Cleanup

const task = new FuturableTask((resolve, reject, utils) => {
  const resource = allocateResource();

  utils.signal.addEventListener('abort', () => {
    resource.cleanup();
  });

  processResource(resource).then(resolve);
});

Abort Controller Integration

const task = FuturableTask.of(() => {
  const controller = new AbortController();

  // Link signals
  task.signal.addEventListener('abort', () => {
    controller.abort();
  });

  return fetch('/api/data', { signal: controller.signal });
});

Conditional Logic

const task = new FuturableTask(async (resolve, reject, { signal }) => {
  for (let i = 0; i < 100; i++) {
    if (signal.aborted) {
      reject(new Error('Cancelled at iteration ' + i));
      return;
    }

    await processItem(i);
  }

  resolve('Complete');
});

Notes

• The signal is aborted when cancel() is called
• Cannot be modified (read-only property)
• Shared across all executions of the task
• Compatible with native AbortSignal APIs
• Once aborted, cannot be reset

See Also

• cancel() - Cancel the task
• onCancel() - Register cancellation callbacks
• run() - Execute the task
• Constructor - Create tasks with signals