n8n-syntax-extension-methods

n8n Extension Methods

Complete reference for all n8n v1.x expression extension methods. ALWAYS use extension methods over raw JavaScript equivalents — they are null-safe and optimized for n8n's expression engine.

Quick Reference — Method Categories

Full method signatures and parameters: references/methods.md Practical examples: references/examples.md Common mistakes: references/anti-patterns.md

Decision Tree — Which Method Category?

What data type are you working with?
|
+-- String value?
|   +-- Need to extract structured data? --> .extractEmail(), .extractUrl(), .extractDomain()
|   +-- Need to validate? --> .isEmail(), .isUrl(), .isEmpty()
|   +-- Need encoding/hashing? --> .urlEncode(), .base64Encode(), .hash()
|   +-- Need case conversion? --> .toTitleCase(), .toSnakeCase(), .toSentenceCase()
|   +-- Need type conversion? --> .toDateTime(), .toBoolean()
|
+-- Array value?
|   +-- Need specific fields from objects? --> .pluck("field1", "field2")
|   +-- Need deduplication? --> .removeDuplicates() or .unique()
|   +-- Need set operations? --> .union(), .intersection(), .difference()
|   +-- Need aggregation? --> .sum(), .average(), .min(), .max()
|   +-- Need restructuring? --> .chunk(), .smartJoin(), .renameKeys()
|
+-- Number value?
|   +-- Need rounding? --> .round(), .ceil(), .floor()
|   +-- Need formatting? --> .format(locale)
|   +-- Need type check? --> .isEven(), .isOdd(), .isInteger()
|   +-- Need conversion? --> .toDateTime(), .toBoolean()
|
+-- Object value?
|   +-- Need to filter fields? --> .keepFieldsContaining(), .removeFieldsContaining()
|   +-- Need to clean nulls? --> .compact()
|   +-- Need to check structure? --> .hasField(), .keys(), .values()
|   +-- Need to combine? --> .merge()
|   +-- Need serialization? --> .toJsonString(), .urlEncode()
|
+-- DateTime value?
|   +-- Need arithmetic? --> .plus(), .minus()
|   +-- Need comparison? --> .equals(), .isBetween(), .diffTo()
|   +-- Need formatting? --> .format(), .toISO(), .toRelative()
|   +-- Need extraction? --> .year, .month, .day, .hour, .weekday
|   +-- Need timezone? --> .setZone(), .toUTC(), .toLocal()
|
+-- Boolean value?
|   +-- Need number? --> .toNumber()
|   +-- Need string? --> .toString()
|
+-- Binary file?
    +-- Need file info? --> .fileName, .fileSize, .mimeType, .fileExtension