n8n Code Nodes

The Code node is powerful and often the wrong tool. The n8n equivalent of dropping into raw SQL when an ORM would do: real cases exist, but the moment a Code node handles logic an expression could, the workflow is harder to read, debug, and maintain. There's also a real perf gap: Code runs in a sandboxed JS runtime, expressions and Edit Fields run in-process, and the per-invocation overhead can be hundreds of times higher in Code (anecdotally ~2ms vs ~600ms for equivalent logic). For hot paths and large item counts, that compounds.

Strong defaults

1. Code node is a last resort. Decision order: expression ({{...}}) → arrow function inside Edit Fields → Code node. The first two paths cover most "transform this data" tasks. Code earns its place for multi-source aggregation, external libraries, stateful work (getWorkflowStaticData), and a few specific patterns documented below.

2. Default to JavaScript. Write JS unless the user explicitly asked for Python ("use Python here," "I'm a Python shop," pasted Python code). Everywhere else in n8n (expressions, Edit Fields) is JS, JS has a curated library allowlist (lodash, crypto, luxon).

Decision tree

Need custom logic?
├── Is it a transformation of one or two fields?
│   └── Expression: {{ $json.foo.toUpperCase() }} or {{ $json.items.map(item => item.name).join(', ') }}
│       Most "just transform this" cases land here.
│
├── Is it multi-line, but pure data shaping (map, filter, reduce, conditional)?