// ❌ ERROR: No code at all
// (Empty code field)

// ❌ ERROR: Code executes but doesn't return anything
const items = $input.all();

// Process items
for (const item of items) {
  console.log(item.json.name);
}

// Forgot to return!

// ❌ ERROR: Early return path exists, but not all paths return
const items = $input.all();

if (items.length === 0) {
  return [];  // ✅ This path returns
}

// Process items
const processed = items.map(item => ({json: item.json}));

// ❌ Forgot to return processed!

// ✅ CORRECT: Always return data
const items = $input.all();

// Process items
const processed = items.map(item => ({
  json: {
    ...item.json,
    processed: true
  }
}));

return processed;  // ✅ Return statement present

// ✅ CORRECT: Return empty array if no items
const items = $input.all();

if (items.length === 0) {
  return [];  // Valid: empty array when no data
}

// Process and return
return items.map(item => ({json: item.json}));

// ✅ CORRECT: All code paths return
const items = $input.all();

if (items.length === 0) {
  return [];
} else if (items.length === 1) {
  return [{json: {single: true, data: items[0].json}}];
} else {
  return items.map(item => ({json: item.json}));
}

// All paths covered

// ❌ WRONG: Using n8n expression syntax in Code node
const userName = "{{ $json.name }}";
const userEmail = "{{ $json.body.email }}";

return [{
  json: {
    name: userName,
    email: userEmail
  }
}];

// Result: Literal string "{{ $json.name }}", NOT the value!

// ❌ WRONG: Trying to evaluate expressions
const value = "{{ $now.toFormat('yyyy-MM-dd') }}";

// ✅ CORRECT: Use JavaScript directly (no {{ }})
const userName = $json.name;
const userEmail = $json.body.email;

return [{
  json: {
    name: userName,
    email: userEmail
  }
}];

// ✅ CORRECT: JavaScript template literals (use backticks)
const message = `Hello, ${$json.name}! Your email is ${$json.email}`;

return [{
  json: {
    greeting: message
  }
}];

// ✅ CORRECT: Direct variable access
const item = $input.first().json;

return [{
  json: {
    name: item.name,
    email: item.email,
    timestamp: new Date().toISOString()  // JavaScript Date, not {{ }}
  }
}];

// WRONG → RIGHT conversions

// ❌ "{{ $json.field }}"
// ✅ $json.field

// ❌ "{{ $now }}"
// ✅ new Date().toISOString()

// ❌ "{{ $node['HTTP Request'].json.data }}"
// ✅ $node["HTTP Request"].json.data

// ❌ `{{ $json.firstName }} {{ $json.lastName }}`
// ✅ `${$json.firstName} ${$json.lastName}`

// ❌ WRONG: Returning object instead of array
return {
  json: {
    result: 'success'
  }
};
// Missing array wrapper []

// ❌ WRONG: Returning array without json wrapper
return [
  {id: 1, name: 'Alice'},
  {id: 2, name: 'Bob'}
];
// Missing json property

// ❌ WRONG: Returning plain value
return "processed";

// ❌ WRONG: Returning items without mapping
return $input.all();
// Works if items already have json property, but not guaranteed

// ❌ WRONG: Incomplete structure
return [{data: {result: 'success'}}];
// Should be {json: {...}}, not {data: {...}}

// ✅ CORRECT: Single result
return [{
  json: {
    result: 'success',
    timestamp: new Date().toISOString()
  }
}];

// ✅ CORRECT: Multiple results
return [
  {json: {id: 1, name: 'Alice'}},
  {json: {id: 2, name: 'Bob'}},
  {json: {id: 3, name: 'Carol'}}
];

// ✅ CORRECT: Transforming array
const items = $input.all();

return items.map(item => ({
  json: {
    id: item.json.id,
    name: item.json.name,
    processed: true
  }
}));

// ✅ CORRECT: Empty result
return [];
// Valid when no data to return

// ✅ CORRECT: Conditional returns
if (shouldProcess) {
  return [{json: {result: 'processed'}}];
} else {
  return [];
}

// Scenario 1: Single object from API
const response = $input.first().json;

// ✅ CORRECT
return [{json: response}];

// ❌ WRONG
return {json: response};


// Scenario 2: Array of objects
const users = $input.all();

// ✅ CORRECT
return users.map(user => ({json: user.json}));

// ❌ WRONG
return users;  // Risky - depends on existing structure


// Scenario 3: Computed result
const total = $input.all().reduce((sum, item) => sum + item.json.amount, 0);

// ✅ CORRECT
return [{json: {total}}];

// ❌ WRONG
return {total};


// Scenario 4: No results
// ✅ CORRECT
return [];

// ❌ WRONG
return null;

// ❌ WRONG: Unescaped quote in string
const message = "It's a nice day";
// Single quote breaks string

// ❌ WRONG: Unbalanced brackets in regex
const pattern = /\{(\w+)\}/;  // JSON storage issue

// ❌ WRONG: Multi-line string with quotes
const html = "
  <div class="container">
    <p>Hello</p>
  </div>
";
// Quote balance issues

// ✅ CORRECT: Escape quotes
const message = "It\\'s a nice day";
// Or use different quotes
const message = "It's a nice day";  // Double quotes work

// ✅ CORRECT: Escape regex properly
const pattern = /\\{(\\w+)\\}/;

// ✅ CORRECT: Template literals for multi-line
const html = `
  <div class="container">
    <p>Hello</p>
  </div>
`;
// Backticks handle multi-line and quotes

// ✅ CORRECT: Escape backslashes
const path = "C:\\\\Users\\\\Documents\\\\file.txt";

// ✅ BEST: Use template literals for complex strings
const message = `User ${name} said: "Hello!"`;

// ✅ BEST: Use template literals for HTML
const html = `
  <div class="${className}">
    <h1>${title}</h1>
    <p>${content}</p>
  </div>
`;

// ✅ BEST: Use template literals for JSON
const jsonString = `{
  "name": "${name}",
  "email": "${email}"
}`;

// ❌ WRONG: No null check - crashes if user doesn't exist
const email = item.json.user.email;

// ❌ WRONG: Assumes array has items
const firstItem = $input.all()[0].json;

// ❌ WRONG: Assumes nested property exists
const city = $json.address.city;

// ❌ WRONG: No validation before array operations
const names = $json.users.map(user => user.name);

// ✅ CORRECT: Optional chaining
const email = item.json?.user?.email || '[email protected]';

// ✅ CORRECT: Check array length
const items = $input.all();

if (items.length === 0) {
  return [];
}

const firstItem = items[0].json;

// ✅ CORRECT: Guard clauses
const data = $input.first().json;

if (!data.address) {
  return [{json: {error: 'No address provided'}}];
}

const city = data.address.city;

// ✅ CORRECT: Default values
const users = $json.users || [];
const names = users.map(user => user.name || 'Unknown');

// ✅ CORRECT: Try-catch for risky operations
try {
  const email = item.json.user.email.toLowerCase();
  return [{json: {email}}];
} catch (error) {
  return [{
    json: {
      error: 'Invalid user data',
      details: error.message
    }
  }];
}

// Pattern 1: Optional chaining (modern, recommended)
const value = data?.nested?.property?.value;

// Pattern 2: Logical OR with default
const value = data.property || 'default';

// Pattern 3: Ternary check
const value = data.property ? data.property : 'default';

// Pattern 4: Guard clause
if (!data.property) {
  return [];
}
const value = data.property;

// Pattern 5: Try-catch
try {
  const value = data.nested.property.value;
} catch (error) {
  const value = 'default';
}

// Webhook data requires extra safety

// ❌ RISKY: Assumes all fields exist
const name = $json.body.user.name;
const email = $json.body.user.email;

// ✅ SAFE: Check each level
const body = $json.body || {};
const user = body.user || {};
const name = user.name || 'Unknown';
const email = user.email || 'no-email';

// ✅ BETTER: Optional chaining
const name = $json.body?.user?.name || 'Unknown';
const email = $json.body?.user?.email || 'no-email';

// ❌ RISKY: No length check
const items = $input.all();
const firstId = items[0].json.id;

// ✅ SAFE: Check length
const items = $input.all();

if (items.length > 0) {
  const firstId = items[0].json.id;
} else {
  // Handle empty case
  return [];
}

// ✅ BETTER: Use $input.first()
const firstItem = $input.first();
const firstId = firstItem.json.id;  // Built-in safety

// ❌ RISKY: Direct access
const config = $json.settings.advanced.timeout;

// ✅ SAFE: Step by step with defaults
const settings = $json.settings || {};
const advanced = settings.advanced || {};
const timeout = advanced.timeout || 30000;

// ✅ BETTER: Optional chaining
const timeout = $json.settings?.advanced?.timeout ?? 30000;
// Note: ?? (nullish coalescing) vs || (logical OR)

// ❌ BLOCKED in task runner sandbox (default since v2.0)
const data = await $helpers.httpRequestWithAuthentication.call(
  this,
  'baseLinkerApi',
  { url: '...', method: 'POST' }
);

// Parent Code node — prepare payloads, then delegate
return $input.all().map(i => ({ json: {
  url: 'https://api.example.com/things',
  method: 'POST',
  body: { sku: i.json.sku }
}}));

// ✅ Works — manual auth header, token came from upstream
const token = $('Get Token').first().json.access_token;

const data = await $helpers.httpRequest({
  url: 'https://api.example.com/data',
  headers: { 'Authorization': `Bearer ${token}` }
});

// ❌ Throws if N8N_BLOCK_ENV_ACCESS_IN_NODE=true
const apiKey = $env.API_KEY;

// ✅ Token arrives as data from an upstream node that used a credential
const apiKey = $('Set Secret').first().json.apiKey;

// Or: secret was attached server-side by an HTTP Request node with the credential
// — your Code node never sees the raw secret, which is the whole point

const items = $input.all();
console.log('Items count:', items.length);
console.log('First item:', items[0]);

// Check browser console (F12) for output

// Debug by returning current state
const items = $input.all();
const processed = items.map(item => ({json: item.json}));

// Return to see what you have
return processed;

try {
  // Your code here
  const result = riskyOperation();
  return [{json: {result}}];
} catch (error) {
  // See what failed
  return [{
    json: {
      error: error.message,
      stack: error.stack
    }
  }];
}

const items = $input.all();

// Check what you received
console.log('Input structure:', JSON.stringify(items[0], null, 2));

// Then process