n8n Code node - Javascript to combine multiple items to 1 items after merging using Append

n8n-combine-items-after-merge-append.js

// This script merges all incoming items into a single object.

const combinedObject = {};

// Loop through each item that flows into this node.
for (const item of items) {
  // Merge the properties of the current item's JSON into our single object.
  // Object.assign() copies all properties from the source (item.json) 
  // to the target (combinedObject).
  // If a key already exists, it will be overwritten by the last one found.
  Object.assign(combinedObject, item.json);
}

// n8n expects an array of items as the output.
// We return an array containing just our single, combined object.
return [{
  json: combinedObject
}];