majiayu000 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"].
Essential Patterns
Pattern 1: Access Current Item Data
{{ $json.name }}
{{ $json.address.city }}
{{ $json["field-with-dashes"] }}
Pattern 2: Access Other Node Output
{{ $("HTTP Request").item.json.data }}
{{ $("Get Users").first().json.email }}
{{ $("Webhook").all().length }}
Pattern 3: Conditional Expressions
{{ $json.status === "active" ? "Yes" : "No" }}
{{ $ifEmpty($json.nickname, $json.fullName) }}
Pattern 4: JMESPath Query
{{ $jmespath($json.data, "[*].name") }}
{{ $jmespath($("Code").all(), "[?json.active==`true`].json.id") }}
Pattern 5: Date Operations (Luxon)
{{ $now.format("yyyy-MM-dd HH:mm:ss") }}
{{ $today.minus({days: 7}).toISO() }}
{{ $now.toRelative() }}
Pattern 6: Static Workflow Data (Persistence)
// In Code node — data persists across executions
const staticData = $getWorkflowStaticData('global');
const lastRun = staticData.lastExecution;
staticData.lastExecution = new Date().toISOString();
// n8n saves automatically on successful execution
Pattern 7: IIFE for Multi-Statement Expressions
{{ (function() { const x = $json.price * 1.21; return x.toFixed(2); })() }}
Pattern 8: Custom Execution Data
// Set data
$execution.customData.set("user_email", "me@example.com");
$execution.customData.setAll({"key1": "val1", "key2": "val2"});
// Get data
const 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
- references/examples.md -- Expression patterns, JMESPath, static data, IIFE patterns
- references/anti-patterns.md -- Expression mistakes, context confusion