Code — JavaScript over the items — is for what the other steps cannot say: reshaping data, a calculation, a signature. It gets the items that reached it, and passes on the items it returns.

Who can do this

Workspace Admins and Editors. It is a paid step: On any paid plan. You can build and test it now; publishing asks you to upgrade.

Steps

  1. Select + where the code should run. In the step picker, open Code and select Code.

  2. Language is JavaScript.

  3. Under Run, choose:

    • Once for all items (the default) — the code runs once, with every item.
    • Once for each item — the code runs once per item, with that item.

  4. Write the code in Code. It starts with an example that passes every item on unchanged:

    const out = [];
for (const item of $input.all()) {
  out.push({ json: { ...item.json } });
}
return out;

  5. Select Run this step. Under the editor, Console shows what the code logged and, if it failed, the error with its line.

What the code can use

Name What it is
$input.all() Every item coming in, each as { json: { … } }.
$input.first(), $input.last(), $input.item The first, last, and first item.
$json The first item's fields.
console.log(…) Writes a line to Console (also info, warn, error).
$now, $today This moment and today's date, in UTC.
$uuid() A new random id.
$sha256(text), $hmacSha256(key, text) Hashes, as hex.
$base64Encode(text), $base64Decode(text) Base64.

No network: that is HTTP Request.

What to return

  • A list of items — [{ json: { … } }, …] — or a list of plain objects, each taken as an item's fields.
  • One object, as one item.
  • An empty list passes nothing on, and the steps after it do not run.

Good to know

  • Limits: 30 seconds, 64 MB of memory, 100 calls deep, and 5 MB returned. Console keeps 200 lines.
  • Values from earlier steps reach the code through $input. {{ }} is not used inside code.
  • Code is a paid step, also when skipped. On Free you can build and test it; publishing asks for a paid plan, and a live run of a workflow with it is skipped if the plan changes.

If something goes wrong

What the run says Why What to do
Line 3 · TypeError: … A value the code reads is missing on an item. Guard it — item.json.text ?? '' — or use Filter before this step. The code read a field that is missing. Guard the value, or filter the items first.
Line 5 · ReferenceError: … A name is used that was never declared. Check its spelling; $input, $json and console are the ones given. A name is misspelt or undeclared. Correct it.
The code cannot be read: … / SyntaxError … Check the brackets and quotes near that line. The code has a typing mistake. Fix the line named.
The code returned nothing. Return a list of items — [{ json: { … } }] — or one object. There is no return. Return the items.
The code returned a value, not items. … / Each item the code returns must be an object — { json: { … } }. It returned a number, text or a list of those. Return objects.
The code ran for more than 30 seconds and was stopped. Look for a loop that never ends. Too slow, or a loop that never ends. Fix the loop, or do less per run.
The code used more than 64 MB of memory and was stopped. Too much memory. Work on fewer items at a time.
The code called itself more than 100 deep and was stopped. Runaway recursion. Fix the function calling itself.
The code returned more than 5 MB. Return less, or split the work. Too much returned. Return less.
There is no code to run. Code is empty. Write some code.