n8n-code-javascript

To return data from an n8n Code node without errors, always format your output as an array of objects using the required [{json: {...}}] structure. This ensures the workflow correctly parses your transformed data.

Choose Run Once for All Items when you need to aggregate multiple inputs or perform complex transformations across the entire dataset. Use Run Once for Each Item for isolated per-item logic.

Access webhook data in an n8n Code node by targeting the payload under the .body property. Using the correct data access patterns like $input.all() or $input.first() prevents common webhook parsing errors.

Yes, you can use built-in helpers in n8n Code nodes to build reliable transformations. Leverage $helpers.httpRequest() for API calls, $jmespath for JSON querying, and DateTime for Luxon date parsing.

The best way to handle null values in n8n JavaScript transformations is to apply safe null handling patterns. Structured guardrails prevent common pitfalls during data access and complex aggregations.

An n8n Code node fails when processing multiple items if the output is not wrapped in the required [{json: {...}}] format or if you select the wrong execution mode for your data access pattern.