n8n Expressions Cheat Sheet: Variables, Functions and Syntax

n8n expressions let you insert dynamic values into any workflow field — pulling data from previous nodes, transforming strings, calculating dates, and applying logic without a full Code node. Expressions use double-curly-brace syntax: {{ }}. Inside those braces you write standard JavaScript, with access to a set of n8n-specific variables. Use expressions for inline transformations and simple conditionals; switch to a Code node when logic spans multiple lines, requires loops, or needs external modules.

Expression Syntax Basics

Any field with the expression toggle (the = icon) accepts an expression. The content inside {{ }} is evaluated as JavaScript at runtime. You can reference the current item, other nodes, workflow metadata, and built-in helpers.

Built-in Variables

String Functions

All standard JavaScript string methods are available. The examples below assume $json.value holds the string being operated on.

Number Functions

Array Functions

Date and Time (Luxon)

n8n uses the Luxon library for all date and time handling. $now and $today both return Luxon DateTime objects, and DateTime is available globally in expressions for parsing custom formats. All times are UTC unless you apply a timezone offset.

Conditional Logic

Use JavaScript conditional operators directly inside expressions for inline branching. These are evaluated at runtime per item.

Real-world conditional examples

{{/* Route based on a status field */}}
{{ $json.status === "active" ? "Send email" : "Skip" }}

{{/* Use a fallback when a name field may be absent */}}
{{ $json.name ?? "Unknown" }}

{{/* Safely access a nested field with an email fallback */}}
{{ $json.user?.email || "no-email@example.com" }}

{{/* Combine nullish coalescing with optional chaining */}}
{{ $json.address?.postcode ?? "Postcode not provided" }}

{{/* Nested ternary — use sparingly for readability */}}
{{ $json.score >= 90 ? "High" : $json.score >= 50 ? "Medium" : "Low" }}

Working with Multiple Items

$json always refers to the current item being processed. To access data from a different node, or from a specific position in a batch, use the node-reference patterns below.

Useful Real-World Expressions

The following expressions are ready to copy into any n8n field that accepts an expression. Each is self-contained.

Dates and times

{{/* Today's date in UK format */}}
{{ $now.toFormat("dd/MM/yyyy") }}

{{/* ISO timestamp for API payloads */}}
{{ $now.toISO() }}

{{/* Add 30 days to a date field and return ISO string */}}
{{ DateTime.fromISO($json.createdAt).plus({days: 30}).toISO() }}

{{/* Format a stored Unix timestamp as a readable UK date */}}
{{ DateTime.fromMillis($json.timestamp).toFormat("dd/MM/yyyy HH:mm") }}

Strings

{{/* Capitalise the first letter of a string */}}
{{ $json.name.charAt(0).toUpperCase() + $json.name.slice(1) }}

{{/* Truncate long text to 100 characters with ellipsis */}}
{{ $json.description.length > 100 ? $json.description.slice(0, 100) + "..." : $json.description }}

{{/* Build a full name from first and last, skipping empty parts */}}
{{ [$json.firstName, $json.lastName].filter(Boolean).join(" ") }}

{{/* Extract domain from an email address */}}
{{ $json.email.split("@")[1] }}

{{/* Pad a number with leading zeros for invoice or reference numbers */}}
{{ String($json.invoiceNumber).padStart(6, "0") }}

Numbers and currency

{{/* Format a number as GBP currency */}}
{{ "£" + Number($json.amount).toFixed(2) }}

{{/* Calculate a percentage */}}
{{ ((($json.completed / $json.total) * 100)).toFixed(1) + "%" }}

{{/* Clamp a value between a min and max */}}
{{ Math.min(Math.max($json.quantity, 1), 100) }}

Arrays and objects

{{/* Check if an array field is non-empty */}}
{{ Array.isArray($json.items) && $json.items.length > 0 }}

{{/* Sum all price values in a line items array */}}
{{ $json.lineItems.reduce((sum, item) => sum + item.price, 0) }}

{{/* Join an array of tags into a comma-separated string */}}
{{ $json.tags.join(", ") }}

{{/* Get distinct values from an array (deduplicate) */}}
{{ [...new Set($json.categories)] }}

Safety and fallbacks

{{/* Safe email fallback when field may be absent */}}
{{ $json.email ?? "unknown@example.com" }}

{{/* Safely access a deeply nested field */}}
{{ $json.order?.customer?.name ?? "Guest" }}

{{/* Return a value only if it passes a type check */}}
{{ typeof $json.count === "number" ? $json.count : 0 }}

Debugging Expressions

Using the expression editor

Click the = toggle on any field to open the expression editor. The panel renders a live preview of the output below the expression as you type, using the actual input data from the last test run of the previous node. The Input tab on the left shows the full $json object available to that field, which is useful for confirming key names before writing an expression.

Inspecting the full input object

{{/* Dump the entire input as a JSON string to inspect its structure */}}
{{ JSON.stringify($json) }}

{{/* Pretty-print with indentation (useful in a Set node's value field) */}}
{{ JSON.stringify($json, null, 2) }}

Common errors and fixes

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