# Background jobs - JavaScript bridge API

> Work that keeps going after the app is closed: a durable auto-save, a periodic sync.

- **Applies to:** AppMint
- **Source:** extracted from the app runtime and its per-method example files; this page is generated from them.
- **HTML:** https://freewebtoapk.com/docs/api/jobs

### `workCancel`

```js
window.WebToApk.workCancel(id: String)
```

No permission needed; results echo as `appmint:work` / window.onAppMintWork.

_Described by its group, Background jobs (WorkManager): durable auto-save + periodic native sync, rather than on its own._

**Example**

Cancels a background job (one-off or repeating) by its id and deletes its saved request.

**Returns:** nothing directly. The `appmint:work` event (and `window.onAppMintWork`) answers `{ id, status: 'cancelled' }`. **Needs:** nothing.

```js
function stopSync() {
  if (!(window.WebToApk && window.WebToApk.workCancel)) return;
  WebToApk.workCancel('sync');
}

window.addEventListener('appmint:work', function (e) {
  if (e.detail.id === 'sync' && e.detail.status === 'cancelled') {
    document.getElementById('sync-status').textContent = 'Background sync is off';
  }
});
```

**Notes:** it answers `cancelled` even when no job had that id. An auto-save that has not been sent yet is dropped, so cancel only when you really do not want it delivered.

### `workEnqueueOnline`

```js
window.WebToApk.workEnqueueOnline(id: String, url: String, method: String, headersJson: String, payload: String)
```

No permission needed; results echo as `appmint:work` / window.onAppMintWork.

_Described by its group, Background jobs (WorkManager): durable auto-save + periodic native sync, rather than on its own._

**Example**

Hands one HTTP request to Android to send when the phone is online - even if the user closes the app or restarts the phone. Use it for a reliable auto-save.

**Returns:** nothing directly. The answer comes as the `appmint:work` event (and `window.onAppMintWork(detail)` if you define it): `{ id, status: 'enqueued' }`, or `{ id, status: 'failed', reason }` with reason `invalid_arguments` (empty id or a URL not starting with `http`) or `enqueue_failed`. **Needs:** nothing.

**Durable auto-save:** the same id replaces a save that has not been sent yet, so the newest state wins.

```js
function autoSave(state, token) {
  if (!(window.WebToApk && window.WebToApk.workEnqueueOnline)) {
    showMessage('Offline auto-save works in the installed app only.');
    return;
  }
  WebToApk.workEnqueueOnline(
    'autosave',                                        // your job id
    'https://api.example.com/save',                    // http(s) URL
    'POST',                                            // POST | PUT | GET ...
    JSON.stringify({ Authorization: 'Bearer ' + token }), // headers as a JSON string
    JSON.stringify(state)                              // body as a string ('' for none)
  );
}

window.addEventListener('appmint:work', function (e) {
  const d = e.detail;
  if (d.id !== 'autosave') return;
  if (d.status === 'enqueued') showSavedBadge('Will sync when online');
  if (d.status === 'failed') showMessage('Could not queue the save: ' + d.reason);
});
```

**Notes:** `enqueued` means Android accepted the job, not that the server got it; there is no event when it is delivered. Delivery rules: a 2xx reply finishes the job; a 4xx reply stops it (no retry); a network error or 5xx retries with growing delays, up to 8 tries. `Content-Type: application/json` is added unless you set one. A `GET` sends no body. The page's JavaScript does not run in the background - only this native request does.

### `workList`

```js
window.WebToApk.workList(requestId: String)
```

No permission needed; results echo as `appmint:work` / window.onAppMintWork.

_Described by its group, Background jobs (WorkManager): durable auto-save + periodic native sync, rather than on its own._

**Example**

Lists the background jobs this app has queued or scheduled.

**Returns:** nothing directly. The `appmint:work` event (and `window.onAppMintWork`) answers `{ requestId, jobs: [{ id, periodic, url, createdAt, pendingDelivery }] }`. `pendingDelivery` is `true` while a one-off job has not been delivered yet (and always for a periodic job). **Needs:** nothing.

**A small Promise wrapper that matches the answer by `requestId`:**

```js
function listJobs() {
  return new Promise(function (resolve) {
    if (!(window.WebToApk && window.WebToApk.workList)) { resolve([]); return; }
    const requestId = 'jobs-' + Date.now();
    function onWork(e) {
      if (String(e.detail.requestId) !== requestId) return;   // not our answer
      window.removeEventListener('appmint:work', onWork);
      resolve(e.detail.jobs || []);
    }
    window.addEventListener('appmint:work', onWork);
    WebToApk.workList(requestId);
  });
}

listJobs().then(function (jobs) {
  const unsent = jobs.filter(function (j) { return !j.periodic && j.pendingDelivery; });
  document.getElementById('unsent').textContent =
    unsent.length ? unsent.length + ' change(s) waiting for network' : 'All changes saved';
});
```

**Notes:** a one-off job leaves the list once it is delivered, rejected with a 4xx, or given up after 8 tries. A numeric `requestId` may come back as a number, so compare with `String(...)`.

### `workSchedulePeriodic`

```js
window.WebToApk.workSchedulePeriodic(id: String, url: String, method: String, headersJson: String, payload: String, intervalMinutes: Int)
```

No permission needed; results echo as `appmint:work` / window.onAppMintWork.

_Described by its group, Background jobs (WorkManager): durable auto-save + periodic native sync, rather than on its own._

**Example**

Schedules a repeating HTTP request that Android sends in the background (when online), even while the app is closed. Good for a sync trigger or a heartbeat.

**Returns:** nothing directly. The answer comes as the `appmint:work` event (and `window.onAppMintWork(detail)`): `{ id, status: 'scheduled', intervalMinutes }`, or `{ id, status: 'failed', reason }` with reason `invalid_arguments` or `schedule_failed`. **Needs:** nothing.

```js
function startBackgroundSync(userId) {
  if (!(window.WebToApk && window.WebToApk.workSchedulePeriodic)) {
    showMessage('Background sync works in the installed app only.');
    return;
  }
  WebToApk.workSchedulePeriodic(
    'sync',                                   // job id (scheduling again updates it)
    'https://api.example.com/sync',
    'POST',
    JSON.stringify({ 'X-User': userId }),     // headers as a JSON string
    JSON.stringify({ userId: userId }),       // the same body is sent every time
    30                                        // minutes; values under 15 become 15
  );
}

// Optional page hook instead of addEventListener:
window.onAppMintWork = function (d) {
  if (d.id === 'sync' && d.status === 'scheduled') {
    console.log('sync every', d.intervalMinutes, 'minutes');
  }
  if (d.status === 'failed') console.warn('job', d.id, 'failed:', d.reason);
};
```

**Notes:** Android decides the exact moment; 15 minutes is the shortest interval, and battery saving can delay runs. The body is fixed when you schedule; to change it, schedule again with the same id. A 4xx reply does not cancel a periodic job; the next run tries again. Stop it with `workCancel('sync')`.