n8n-code-javascript

To write JavaScript for multiple items in an n8n Code node, use Run Once for All Items mode, access input data with $input.all(), process the array with map(), and return an array of objects containing a json property like [{json: {...}}].

The correct return format for n8n Code nodes is an array of objects, where each object contains a json property. Returning malformed structures without the json key prevents downstream nodes from accessing the processed data correctly.

An n8n Code node fails with expression syntax because it expects pure JavaScript, not n8n expressions. You must write standard JavaScript code to access data, using built-in helpers like $helpers.httpRequest instead of inline expressions.

Yes, you can use built-in helpers in n8n Code nodes to perform date calculations with DateTime (Luxon), query JSON with $jmespath, and make API calls using $helpers.httpRequest directly within your JavaScript transformations.

To access webhook payload data safely in an n8n Code node, reference the incoming item's json property and extract the payload under the .body object, ensuring secure data handling before performing transformations or API calls.

Use Run Once for Each Item in n8n when processing individual items sequentially with $input.item, and use Run Once for All Items when aggregating data or performing batch calculations across multiple items with $input.all().