async-patterns

Async/Await Patterns for FDK Validation

When to use: fdk validate shows async-related errors

Common Async Errors

Error 1: Async without await

Lint Error: Async function has no 'await' expression

Fix: Remove async keyword OR add actual await

// [INVALID] WRONG: async without await
exports = {
  onAppInstallHandler: async function() {
    console.log('Installed');
  }
};

// [VALID] CORRECT: Remove async
exports = {
  onAppInstallHandler: function() {
    console.log('Installed');
  }
};

// [VALID] CORRECT: Add await
exports = {
  onAppInstallHandler: async function() {
    await $db.set('installed', { timestamp: Date.now() });
    console.log('Installed');
  }
};

Error 2: Async Variable Scoping (Frontend)

Warning: Async function may cause race conditions in frontend initialization

Fix: Use IIFE pattern

// [INVALID] WRONG: Top-level async causes race conditions
async function init() {
  const client = await app.initialized();
  // ... rest of code
}
init();

// [VALID] CORRECT: IIFE pattern
(async function() {
  const client = await app.initialized();
  // ... rest of code
})();

Error 3: Unhandled Promise Rejection

Warning: Expected rejection to be handled

Fix: Wrap in try/catch

// [INVALID] WRONG: No error handling
exports = {
  fetchData: async function() {
    const result = await $request.invokeTemplate('api', {});
    return result;
  }
};

// [VALID] CORRECT: Try/catch wrapper
exports = {
  fetchData: async function() {
    try {
      const result = await $request.invokeTemplate('api', {});
      return { success: true, data: result };
    } catch (e) {
      console.error('API call failed:', e.message);
      return { success: false, error: e.message };
    }
  }
};

Frontend Async Patterns

Pattern 1: App Initialization (IIFE)

// [VALID] CORRECT: Standard frontend pattern
(async function() {
  const client = await app.initialized();

  document.getElementById('btn').addEventListener('fwClick', async () => {
    try {
      const response = await client.request.invoke('getData', {});
      displayResult(response);
    } catch (e) {
      showError(e.message);
    }
  });
})();