Openaec Foundation N8n Claude Skill Package N8n Syntax Expressions

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

Other Node Output

Workflow & Execution Metadata

Environment & Configuration

Date & Time (Luxon DateTime)

Node Execution Context

Utility Functions

HTTP Response (HTTP Request Node Only)

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:

Expression Context Rules

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

Official Sources

• https://docs.n8n.io/code/expressions/
• https://docs.n8n.io/code/builtin/overview/
• https://docs.n8n.io/code/builtin/current-node-input/
• https://docs.n8n.io/code/builtin/output-other-nodes/
• https://docs.n8n.io/code/builtin/n8n-metadata/
• https://docs.n8n.io/data/jmespath/

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