Connect WhatsApp Web

const client = OmniZapi.newClient({ publicKey: 'YOUR_PUBLIC_KEY' });
const channelId = 'CHANNEL_ID';

const response = await client.connect({
  channelId,
  getQRCode: async () => {
    const res = await fetch(`/api/omni/channels/${encodeURIComponent(channelId)}/qr-code`, { credentials: 'include' });
    const body = await res.json();
    // Reject with status and message: the window shows the message when the status is 4xx
    if (!res.ok) throw { status: res.status, message: body.message ?? null };
    // With no value and no connected: true, the window takes it that the QR Code is not ready yet
    return { connected: body.connected === true, value: body.qrcode ?? undefined };
  },
});

app.get('/api/omni/channels/:id/qr-code', requireSessionAndChannelOwnership, async (req, res) => {
  const response = await fetch(
    `https://api.omni.z-api.io/v1/channels/${encodeURIComponent(req.params.id)}/zapi/qr-code/image`,
    { headers: { Authorization: `Bearer ${process.env.OMNI_SECRET_KEY}` } },
  );
  const body = await response.json();
  if (!response.ok) {
    // The API error comes in error.errors[0]; pass on only the text
    return res.status(response.status).json({ message: body?.error?.errors?.[0]?.description ?? null });
  }
  res.json({ qrcode: body.qrcode, connected: body.connected });
});