Write code and expressions in n8n - JavaScript, Python, built-in variables, data transformation
Master n8n's expression syntax and code capabilities.
Expressions in n8n use {{ }} or ={{ }} syntax to reference data dynamically.
$json - Current Item Data// Access fields from current item
{{ $json.name }} // Direct field
{{ $json.user.email }} // Nested field
{{ $json["field-name"] }} // Fields with special chars
{{ $json.items[0].id }} // Array access
$input - Input Operations// Get all input items
{{ $input.all() }} // Array of all items
{{ $input.first() }} // First item
{{ $input.last() }} // Last item
{{ $input.item }} // Current item (in loop)
// Get specific item
{{ $input.item(0) }} // Item at index
{{ $input.item(0).json.name }} // Field from item
$binary - Binary Data// Access file/binary data
{{ $binary.data }} // Binary data object
{{ $binary.data.fileName }} // Original filename
{{ $binary.data.mimeType }} // MIME type
{{ $binary.data.fileSize }} // Size in bytes
$node - Other Node Data// Reference output from specific node
{{ $node["HTTP Request"].json.response }}
{{ $node["Code"].json.result }}
// Get all items from node
{{ $node["Split"].json }}
$execution - Execution Info{{ $execution.id }} // Execution ID
{{ $execution.mode }} // "manual" or "trigger"
{{ $execution.resumeUrl }} // URL to resume (Wait node)
{{ $execution.customData }} // Custom execution data
$workflow - Workflow Info{{ $workflow.id }} // Workflow ID
{{ $workflow.name }} // Workflow name
{{ $workflow.active }} // Is active (boolean)
$env - Environment Variables{{ $env.MY_API_KEY }} // Access env var
{{ $env["DATABASE_URL"] }} // Env var with special chars
$vars - Workflow Variables{{ $vars.baseUrl }} // Workflow-level variable
{{ $vars.apiVersion }} // Defined in workflow settings
$now and $today{{ $now }} // Current datetime (ISO)
{{ $today }} // Today's date (ISO)
{{ $now.toMillis() }} // Unix timestamp (ms)
{{ $now.format('yyyy-MM-dd') }} // Formatted date
{{ $itemIndex }} // Current item index (0-based)
{{ $runIndex }} // Current run index
{{ $prevNode }} // Previous node reference
{{ $position }} // Node position in workflow
{{ $json.text.toUpperCase() }}
{{ $json.text.toLowerCase() }}
{{ $json.text.trim() }}
{{ $json.text.split(',') }}
{{ $json.text.replace('old', 'new') }}
{{ $json.text.slice(0, 10) }}
{{ $json.text.includes('search') }}
{{ $json.text.startsWith('prefix') }}
{{ $json.text.length }}
{{ Math.round($json.price) }}
{{ Math.floor($json.value) }}
{{ Math.ceil($json.value) }}
{{ Math.abs($json.diff) }}
{{ Math.max($json.a, $json.b) }}
{{ Number.parseFloat($json.str) }}
{{ Number.parseInt($json.str, 10) }}
{{ $json.amount.toFixed(2) }}
{{ $json.items.length }}
{{ $json.items.map(i => i.name) }}
{{ $json.items.filter(i => i.active) }}
{{ $json.items.find(i => i.id === '123') }}
{{ $json.items.includes('value') }}
{{ $json.items.join(', ') }}
{{ $json.items.slice(0, 5) }}
{{ $json.items.sort((a,b) => a.name.localeCompare(b.name)) }}
{{ $json.items.reverse() }}
{{ [...new Set($json.items)] }} // Unique values
{{ Object.keys($json.data) }}
{{ Object.values($json.data) }}
{{ Object.entries($json.data) }}
{{ JSON.stringify($json.data) }}
{{ JSON.parse($json.jsonString) }}
{{ {...$json.obj1, ...$json.obj2} }} // Merge objects
// Luxon DateTime (built-in)
{{ DateTime.now().toISO() }}
{{ DateTime.fromISO($json.date).toFormat('MM/dd/yyyy') }}
{{ DateTime.now().plus({days: 7}).toISO() }}
{{ DateTime.now().minus({hours: 2}).toISO() }}
{{ DateTime.now().startOf('day').toISO() }}
{{ DateTime.now().endOf('month').toISO() }}
// Comparison
{{ DateTime.fromISO($json.date) > DateTime.now() }}
{{ DateTime.fromISO($json.date).diff(DateTime.now(), 'days').days }}
// Conditionals
{{ $json.status === 'active' ? 'Yes' : 'No' }}
{{ $json.value ?? 'default' }} // Nullish coalescing
{{ $json.name || 'Anonymous' }} // Falsy fallback
// Type checking
{{ typeof $json.value }}
{{ Array.isArray($json.items) }}
{{ $json.value === null }}
{{ $json.value === undefined }}
// Process all items - must return array of {json: {...}} objects
const results = [];
for (const item of $input.all()) {
// Process each item
results.push({
json: {
original: item.json,
processed: true,
timestamp: new Date().toISOString()
}
});
}
return results;
// Return single item
return [{
json: {
result: 'processed',
data: $json.input
}
}];
// HTTP request example
const response = await fetch('https://api.example.com/data', {
method: 'POST',
headers: {'Content-Type': 'application/json'},
body: JSON.stringify({input: $json.data})
});
const data = await response.json();
return [{json: data}];
// Access binary data
const binaryData = $input.first().binary;
const fileName = binaryData.data.fileName;
// Create binary output
const csvContent = 'name,email\nJohn,[email protected]';
const base64 = Buffer.from(csvContent).toString('base64');
return [{
json: {exported: true},
binary: {
data: {
data: base64,
mimeType: 'text/csv',
fileName: 'export.csv'
}
}
}];
try {
const result = await riskyOperation($json.data);
return [{json: {success: true, result}}];
} catch (error) {
// Option 1: Return error info
return [{json: {success: false, error: error.message}}];
// Option 2: Throw to trigger error workflow
throw new Error(`Processing failed: ${error.message}`);
}
// Get data from another node
const httpData = $node['HTTP Request'].json;
// Get all items from a node
const allItems = $items('Split Out');
// Get environment variable
const apiKey = $env.API_KEY;
# Process all items
results = []
for item in _input.all():
data = item["json"]
results.append({
"json": {
"original": data,
"processed": True,
"uppercase": data.get("text", "").upper()
}
})
return results
import json
from datetime import datetime
# Access current item
data = _json
# Transform data
result = {
"json": {
"id": data.get("id"),
"name": data.get("name", "").strip(),
"score": int(data.get("score", 0)) * 2,
"processed_at": datetime.now().isoformat()
}
}
return [result]
# Available: json, datetime, re, math, urllib
import re
import math
text = _json.get("content", "")
emails = re.findall(r'[\w\.-]+@[\w\.-]+', text)
return [{
"json": {
"emails": emails,
"count": len(emails)
}
}]
const item = $json;
return [{
json: {
id: item.id,
userName: item.user.name,
userEmail: item.user.email,
addressCity: item.address?.city ?? 'Unknown'
}
}];
const items = $input.all();
const grouped = {};
for (const item of items) {
const key = item.json.category;
if (!grouped[key]) grouped[key] = [];
grouped[key].push(item.json);
}
return Object.entries(grouped).map(([category, items]) => ({
json: {category, items, count: items.length}
}));
const items = $input.all();
const seen = new Set();
const unique = [];
for (const item of items) {
const key = item.json.id;
if (!seen.has(key)) {
seen.add(key);
unique.push(item);
}
}
return unique;
// Convert rows to columns
const items = $input.all();
const pivoted = {};
for (const item of items) {
const {key, value} = item.json;
pivoted[key] = value;
}
return [{json: pivoted}];
const items = $input.all();
const batchSize = 10;
const batches = [];
for (let i = 0; i < items.length; i += batchSize) {
batches.push({
json: {
batch: Math.floor(i / batchSize) + 1,
items: items.slice(i, i + batchSize).map(item => item.json)
}
});
}
return batches;
const required = ['email', 'name', 'amount'];
const missing = required.filter(f => !$json[f]);
if (missing.length > 0) {
throw new Error(`Missing required fields: ${missing.join(', ')}`);
}
return [{json: {...$json, validated: true}}];
let parsed;
try {
parsed = JSON.parse($json.jsonString);
} catch (e) {
throw new Error('Invalid JSON input');
}
return [{json: parsed}];
const amount = $json.amount;
const formatted = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD'
}).format(amount);
return [{json: {...$json, formattedAmount: formatted}}];
function uuid() {
return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, c => {
const r = Math.random() * 16 | 0;
const v = c === 'x' ? r : (r & 0x3 | 0x8);
return v.toString(16);
});
}
return [{json: {...$json, id: uuid()}}];
// Track calls for rate limiting
const execId = $execution.id;
const callCount = $workflow.staticData?.callCount ?? 0;
$workflow.staticData = {
callCount: callCount + 1,
lastCall: Date.now()
};
return [{json: {...$json, callNumber: callCount + 1}}];
console.log('Input:', JSON.stringify($json, null, 2));
console.log('Item count:', $input.all().length);
console.log('Execution:', $execution.id);
return [{
json: {
inputType: typeof $json,
keys: Object.keys($json),
itemCount: $input.all().length,
hasEmail: 'email' in $json,
emailType: typeof $json.email
}
}];
EXPRESSION:
{{ [expression here] }}
Returns: [expected output]
CODE PATTERN:
Purpose: [what it does]
```javascript
[code here]
Input: [sample input] Output: [sample output]