n8n-code-javascript

JavaScript Code nodes in n8n transform input items by accessing data via $input.all, $input.first, or $input.item(), then returning an array of {json: ...} objects. Use $helpers.httpRequest for HTTP calls, DateTime (Luxon) for date operations, and $jmespath for JSON querying. The node runs in either Run Once for All Items or Run Once for Each Item mode depending on your batch requirements.

Production patterns include mapping and filtering input arrays, aggregating values across items, and enriching data with external API responses. Access inter-node data through $node references and webhook payloads via .body. Use error prevention patterns and safe data access to avoid runtime failures in batch processing workflows.

Yes, $helpers.httpRequest enables cross-node HTTP requests within Code nodes for fetching external data or calling APIs. Combine this with data transformation logic to enrich items, validate against external sources, or aggregate responses—all within a single code node without separate HTTP Request nodes.

Webhook payloads are accessed through the .body property within Code nodes. Extract and transform webhook data using standard JavaScript, then reference it alongside other node outputs via $node. This enables parsing incoming webhooks, filtering fields, and routing the transformed payload downstream.

Run Once for All Items processes the entire input batch in a single execution, accessed via $input.all(), enabling aggregation and cross-item operations. Run Once for Each Item executes the code separately for each input item using $input.item(), ideal for per-item transformations and API enrichment at scale.

Use error prevention patterns documented in the Skill—validate data before access, handle null/undefined safely, and test transformations incrementally. The Skill covers CI considerations and debugging practices to catch issues before production deployment in workflows.