n8n-code-javascript

Use $input.all() for batch processing of all items, $input.first() for single-item operations, and $input.item only in Run Once for Each Item mode. Access fields via the .json property, such as $input.first().json.fieldName.

The Code node must return an array of objects where each object has a json property, in the form [{json: {...}}]. Returning a plain object, a value without the json wrapper, or nothing causes validation errors.

Webhook nodes nest the payload under a body property, so $json.name returns undefined. Access fields via $json.body.name, and use $json.query for URL parameters and $json.headers for HTTP headers.

No, expression syntax with double curly braces only works in other nodes like Set or IF. Inside Code nodes, write plain JavaScript such as $json.field, and use template literals with backticks for string interpolation.

Use the built-in $helpers.httpRequest() function with method, url, headers, body, and query string options. External npm packages like axios are not available, so this helper is the supported approach for API calls.

Use a Code node for complex transformations, multi-step conditionals, aggregations across items, or recursive logic. For simple field mapping, filtering, or single conditions, the Set, Filter, or IF nodes are simpler choices.