Expression Syntax
Complete reference for n8n expression syntax — variables, data references, built-in methods, and common patterns.
Expression Basics
Expressions use double curly braces: {{ expression }}. They can reference data from previous nodes, environment variables, and built-in functions.
{{ $json.fieldName }}
{{ $json["field with spaces"] }}
{{ $json.nested.field }}
Built-in Variables
Current Item Data
| Variable |
Description |
$json |
Current item's JSON data (alias for $input.item.json) |
$binary |
Current item's binary data |
$input.item.json |
Full form of current item |
$input.all() |
All items from previous node (array) |
$input.first() |
First item from previous node |
$input.last() |
Last item from previous node |
Node References
| Variable |
Description |
$node["Node Name"].json |
Data from a specific named node |
$("Node Name").item.json |
Same as above (shorthand) |
$("Node Name").all() |
All items from a specific node |
$("Node Name").first() |
First item from a specific node |
Workflow & Execution
| Variable |
Description |
$workflow.id |
Current workflow ID |
$workflow.name |
Current workflow name |
$workflow.active |
Whether workflow is active |
$execution.id |
Current execution ID |
$execution.mode |
Execution mode (manual, trigger, webhook) |
$execution.resumeUrl |
URL to resume a waiting execution |
Environment & Parameters
| Variable |
Description |
$env.VARIABLE_NAME |
Environment variable |
$vars.variableName |
n8n workflow variable |
$parameter.fieldName |
Current node parameter value |
$itemIndex |
Index of current item in the array |
$runIndex |
Current run index (for loops) |
$now |
Current DateTime |
$today |
Today's date at midnight |
Trigger Data
| Variable |
Description |
$webhookData |
Data from webhook trigger |
$execution.customData |
Custom data set during execution |
String Methods
{{ $json.name.toUpperCase() }}
{{ $json.name.toLowerCase() }}
{{ $json.email.includes("@gmail.com") }}
{{ $json.text.replace("old", "new") }}
{{ $json.text.replaceAll("old", "new") }}
{{ $json.name.trim() }}
{{ $json.name.length }}
{{ $json.text.slice(0, 100) }}
{{ $json.text.split(",") }}
{{ $json.name.startsWith("Mr") }}
{{ $json.name.endsWith("Jr") }}
Number Methods
{{ $json.price.toFixed(2) }}
{{ Math.round($json.value) }}
{{ Math.floor($json.value) }}
{{ Math.ceil($json.value) }}
{{ Math.max($json.a, $json.b) }}
{{ Math.min($json.a, $json.b) }}
{{ parseInt($json.stringNumber) }}
{{ parseFloat($json.stringDecimal) }}
Array Methods
{{ $json.items.length }}
{{ $json.items.filter(item => item.status === "active") }}
{{ $json.items.map(item => item.name) }}
{{ $json.items.find(item => item.id === 123) }}
{{ $json.items.some(item => item.price > 100) }}
{{ $json.items.every(item => item.active) }}
{{ $json.tags.join(", ") }}
{{ $json.items.sort((a, b) => a.price - b.price) }}
{{ $json.items.reduce((sum, item) => sum + item.price, 0) }}
{{ $json.items.includes("value") }}
Date and Time
Using Luxon (built-in)
{{ $now.toISO() }} // 2024-01-15T10:30:00.000Z
{{ $now.toFormat("yyyy-MM-dd") }} // 2024-01-15
{{ $now.toFormat("dd/MM/yyyy HH:mm") }} // 15/01/2024 10:30
{{ $now.plus({ days: 7 }).toISO() }} // 7 days from now
{{ $now.minus({ hours: 2 }).toISO() }} // 2 hours ago
{{ $now.startOf("day").toISO() }} // Start of today
{{ $now.endOf("month").toISO() }} // End of current month
{{ $now.weekday }} // Day of week (1=Mon, 7=Sun)
{{ $now.year }} // Current year
{{ $now.month }} // Current month (1-12)
{{ $now.day }} // Current day of month
Parsing Dates
{{ DateTime.fromISO($json.date) }}
{{ DateTime.fromFormat($json.date, "dd/MM/yyyy") }}
{{ DateTime.fromMillis($json.timestamp) }}
{{ DateTime.fromSeconds($json.unixTimestamp) }}
Date Comparisons
{{ DateTime.fromISO($json.dueDate) < $now }} // Is past due?
{{ DateTime.fromISO($json.dueDate).diff($now, "days").days }} // Days until due
JMESPath Expressions
n8n supports JMESPath for complex data queries in the JMESPath expression mode:
// Select nested field
people[*].name
// Filter array
people[?age > `30`]
// Sort
sort_by(people, &name)
// Select multiple fields
people[*].{name: name, email: email}
// Flatten nested arrays
orders[*].items[]
// Conditions
people[?status == 'active'].name
Common Patterns
Conditional Values (Ternary)
{{ $json.status === "active" ? "Yes" : "No" }}
{{ $json.price > 100 ? "Premium" : "Standard" }}
{{ $json.email ? $json.email : "no-email@example.com" }}
Null/Undefined Handling
{{ $json.field ?? "default value" }} // Nullish coalescing
{{ $json.nested?.field ?? "missing" }} // Optional chaining
{{ $json.items?.length ?? 0 }} // Safe array length
String Templates
{{ `Hello ${$json.firstName} ${$json.lastName}` }}
{{ `Order #${$json.id} - Total: $${$json.total.toFixed(2)}` }}
Object Manipulation
{{ Object.keys($json) }} // Get all field names
{{ Object.values($json) }} // Get all values
{{ Object.entries($json) }} // Get key-value pairs
{{ JSON.stringify($json.data) }} // Serialize to string
{{ JSON.parse($json.jsonString) }} // Parse JSON string
Combine Data from Multiple Nodes
{{ $("HTTP Request").first().json.apiData }}
{{ $("Customers DB").all().map(i => i.json.email) }}
{{ $("Config").first().json.setting ?? "default" }}
Common Mistakes and Fixes
| Mistake |
Fix |
{{ $json.field name }} |
{{ $json["field name"] }} — use brackets for spaces |
{{ $json.items[0] }} in empty array |
{{ $json.items?.[0] ?? null }} — check for empty |
{{ $node.NodeName.json }} |
{{ $("Node Name").item.json }} — use function syntax |
{{ $json.date + 1 }} for adding days |
{{ DateTime.fromISO($json.date).plus({days:1}).toISO() }} |
{{ $json.price * 1.1 }} returns string |
{{ Number($json.price) * 1.1 }} — ensure numeric |
| Accessing data from parallel branch |
Use $("Node Name") to reference specific node by name |
Expression Modes
n8n supports two expression modes in different contexts:
- JavaScript — default for most fields, uses
{{ }} syntax
- JMESPath — available in specific nodes, for complex data querying
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