Use when writing n8n expressions, accessing node data, using JMESPath, or debugging expression errors. Prevents incorrect variable references and expression context mistakes. Covers all built-in variables ($json, $input, $node, $workflow, $execution, $env, $vars, $now, $today), JMESPath queries ($jmespath), paired items, static workflow data ($getWorkflowStaticData), utility functions ($ifEmpty), and expression context rules. Keywords: n8n, expressions, $json, $input, $node, JMESPath, $env, $vars,, access data, reference previous node, dynamic value, variable syntax, how to get field value. paired items, $getWorkflowStaticData.
license
MIT
compatibility
Designed for Claude Code. Requires n8n v1.x.
metadata
{"author":"OpenAEC-Foundation","version":"1.0"}
n8n-syntax-expressions
Quick Reference
Expression Syntax
All n8n expressions use double-curly-brace syntax inside node parameter fields:
{{ expression }}
Expressions support standard JavaScript operations plus n8n-specific built-in variables.
Current Node Input
Variable
Returns
Description
$json
Object
Shorthand for $input.item.json — current item's JSON data
$binary
Object
Shorthand for $input.item.binary — current item's binary data
$input.item
Item
The input item currently being processed
$input.all()
Array<Item>
All input items from the current node
$input.first()
Item
First input item
$input.last()
Item
Last input item
$input.params
Object
Node configuration settings and operation parameters
Other Node Output
Variable
Returns
Description
$("node-name").all()
Array<Item>
All items from named node output
$("node-name").first()
Item
First item from named node
$("node-name").last()
Item
Last item from named node
$("node-name").item
Item
Linked item via paired items tracking
$("node-name").itemMatching(index)
Item
Traces back to matching item (preferred in Code node)
$("node-name").params
Object
Query settings/parameters of named node
$("node-name").context
Object
Only available with Loop Over Items node
$("node-name").isExecuted
Boolean
True if the node has executed
Workflow & Execution Metadata
Variable
Returns
Description
$workflow.id
String
Workflow ID
$workflow.name
String
Workflow name
$workflow.active
Boolean
Whether workflow is active
$execution.id
String
Unique execution ID
$execution.mode
String
"test", "production", or "evaluation"
$execution.resumeUrl
String
Webhook URL to resume at a Wait node
$execution.resumeFormUrl
String
URL for Wait node form
$execution.customData
CustomData
Get/set custom execution data
Environment & Configuration
Variable
Returns
Description
$env
Object
Instance environment variables
$vars
Object
Active environment variables (all strings)
$secrets
Object
External secrets (NOT available in Code node)
Date & Time (Luxon DateTime)
Variable
Returns
Description
$now
DateTime
Current moment, respects workflow timezone
$today
DateTime
Midnight at start of current day
Node Execution Context
Variable
Returns
Description
$prevNode.name
String
Name of previous node
$prevNode.outputIndex
Number
Output connector index
$prevNode.runIndex
Number
Run of previous node
$runIndex
Number
How many times current node has executed (zero-based)
$itemIndex
Number
Current item position (NOT available in Code node)
$parameter
Object
Configuration settings of current node
$nodeVersion
Number
Current node version
$pageCount
Number
Results pages fetched (HTTP Request node only)
Utility Functions
Function
Returns
Description
$ifEmpty(value, fallback)
any
Returns value if non-empty, otherwise fallback
$jmespath(object, searchString)
any
JMESPath query on a JSON object
$getWorkflowStaticData(type)
Object
Persistent data. Type: "global" or "node"
HTTP Response (HTTP Request Node Only)
Variable
Returns
Description
$response.body
Object
Response body from last HTTP call
$response.headers
Object
Response headers
$response.statusCode
Number
HTTP status code
$response.statusMessage
String
Optional status message
Critical Warnings
NEVER use $itemIndex in the Code node -- it is NOT available there. Use a loop counter or items.indexOf() instead.
NEVER use $secrets in the Code node -- it is NOT available there. Pass secret values via node parameters or use $env / $vars instead.
NEVER reverse the parameter order of $jmespath() -- it is $jmespath(object, searchString), NOT $jmespath(searchString, object). The n8n implementation differs from the JMESPath specification's search(searchString, object) pattern.
NEVER use new Date() in expressions -- ALWAYS use Luxon's $now, $today, DateTime.fromISO(), or DateTime.fromFormat() for consistent timezone handling.
NEVER rely on $getWorkflowStaticData() during manual test executions -- static data requires an active workflow with a trigger or webhook.
NEVER store large data objects in workflow static data -- keep it small. Large data causes performance degradation.
ALWAYS use $json as the primary way to access current item data -- it is shorthand for $input.item.json.
ALWAYS use $("Node Name").item in expressions for linked item access. In Code nodes, use $("Node Name").itemMatching(index) instead.
ALWAYS use $ifEmpty(value, fallback) for safe null/undefined handling -- it covers "", [], {}, null, and undefined.
ALWAYS use bracket notation for dynamic property access: $json["field-with-dashes"].
// Set data
$execution.customData.set("user_email", "me@example.com");
$execution.customData.setAll({"key1": "val1", "key2": "val2"});
// Get dataconst email = $execution.customData.get("user_email");
const all = $execution.customData.getAll();
Pattern 9: Paired Items (Item Linking)
Every output item links back to the input items that produced it. This enables:
Automatic item resolution in drag-and-drop mapping
$("Node").item — access the linked item in expressions
$("Node").itemMatching(index) — trace item origin in Code node
When a node processes multiple items, {{ $json.fruit }} dynamically resolves to each item's value during iteration.
$ifEmpty Behavior
$ifEmpty(value, fallback) returns fallback when value is any of:
Value
Considered Empty
""
Yes
[]
Yes
{}
Yes
null
Yes
undefined
Yes
0
No
false
No
Expression Context Rules
Context
Available Variables
Node parameter fields
ALL $ variables
Code node (JavaScript)
ALL except $itemIndex and $secrets
Code node (Python)
_ prefix variants (e.g., _json, _env, _vars)
Credential fields
$credentials object only
HTTP Request node
ALL plus $response and $pageCount
Loop Over Items
ALL plus $("Loop Node").context
Reference Links
references/methods.md -- All $ variables with signatures, return types, descriptions
