denoland/deno · error · TypeError

Failed to construct 'Notification': 1 argument required, but

Error message

Failed to construct 'Notification': 1 argument required, but only 0 present.

What it means

The Web Notifications API constructor is `new Notification(title, options?)` and shows the notification immediately; the title is mandatory. The desktop runtime's JS wrapper (embedded in cli/rt/desktop.rs) checks `arguments.length < 1` and throws this TypeError when the constructor is called with zero arguments.

Source

Thrown at cli/rt/desktop.rs:498

        return out;
      }
      return new TextEncoder().encode(decodeURIComponent(payload));
    } catch {
      return null;
    }
  }

  const NotificationPrototype = NotificationNative.prototype;
  Object.setPrototypeOf(NotificationPrototype, EventTarget.prototype);

  const notifications = new Map();
  // The Web Notifications API constructor is `new Notification(title, options?)`
  // and shows the notification immediately. The native constructor takes
  // a third arg for pre-decoded icon bytes so the icon URL → bytes step
  // happens on the JS side (sync data: URL decoding only).
  const Notification = function Notification(title, options) {
    if (arguments.length < 1) {
      throw new TypeError(
        "Failed to construct 'Notification': 1 argument required, but only 0 present.",
      );
    }
    const t = String(title);
    const opts = options ?? {};
    const iconBytes = decodeDataUrlSync(opts.icon);
    const instance = new NotificationNative(t, opts, iconBytes ?? undefined);
    if (instance.notificationId !== 0) {
      notifications.set(instance.notificationId, instance);
    } else {
      // Backend didn't show it (no support / failure). The native side
      // already emitted a NotificationError event; nothing to track here.
    }
    return instance;
  };
  Object.setPrototypeOf(Notification, NotificationNative);
  Object.setPrototypeOf(Notification.prototype, NotificationPrototype);
  Notification.prototype.constructor = Notification;

View on GitHub (pinned to 89f33cbef2)

Solutions

1. Pass a title string as the first argument: new Notification('Backup complete').
2. Default the title before constructing: new Notification(title ?? 'Alert').
3. Skip showing the notification when no title exists instead of constructing with none.

Example fix

// before
new Notification();
// after
new Notification(title ?? 'Update available');

if (typeof title !== 'string' || title.length === 0) {
  console.warn('Notification skipped: no title');
} else {
  new Notification(title, options);
}

When it happens

Trigger: Calling `new Notification()` with no arguments in the Deno desktop runtime. Note: `new Notification(undefined)` does NOT trigger it, because undefined is coerced to the title string 'undefined'.

Common situations: Notification titles sourced from config or state that was never populated; ported code that assumed a default title; refactors that dropped the first argument.

Related errors

• Notification.requestPermission: not supported by this platfo
• Failed to execute 'query' on 'Permissions': descriptor requi
• Unexpected 'name' field in options, bench name is already pr
• The bench function must have a name
• Unexpected second argument to Deno.bench()

AI-assisted analysis of denoland/deno@89f33cbef2 (2026-08-16). Data as JSON: /api/errors/440b584d7e0adc1d. Report an issue: GitHub.