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Code

Run your own JavaScript in a step to reshape data the other apps can’t.

1 action · No connection needed

Do things in Code

Add a Code step. Choose the row to see all its fields.

Map values under Inputs, read them as inputs, and return what the next steps should get:

JavaScript
const name = inputs.name || "world";
return { greeting: `Hello, ${name}!` };

Later steps read what you return as {{steps.<name>.result}}. You can also read trigger, steps, $vars, $now and $today, and write to the log with console.log.

Versions

A new Code step is on 2.0.0, which replaces nothing inside the code: never write {{ }} there. It is refused when you check or publish. Older steps stay on 1.0.0, which pastes each {{ }} into the program text before it runs, so whoever calls the trigger can change the program. Upgrade one with Upgrade to 2.0.0 in the step, or from the API.

JavaScript that doesn’t parse saves as a draft, but publishing it is refused with code_syntax_error and the line. A 1.0.0 step that holds {{ }} is checked only when it runs.

Intl.NumberFormat and Intl.DateTimeFormat, and toLocaleString on numbers and dates, format in about 1,100 locales, as Node writes them: new Intl.DateTimeFormat("en-CA").format(date) gives a date such as 2026-10-26. A locale GoRunner doesn’t have falls back as in Node, to its language, then en-US. See Expressions.

Later steps read a step’s output by its name: see Use data from earlier steps.

Limits

  • There is no npm, require, import or network. To call an API, use an HTTP Request step and map its reply in as an input.
  • A Code step stops after 30 seconds, or sooner if you set a shorter Timeout (under Error handling). It may use up to 256 MB of memory. On a self-hosted installation, SCRIPT_MEMORY_LIMIT_MB changes that.
  • Code is at most 256 KB, and the log keeps 1 MB. A step may pass on at most 16 MB, so a larger result fails the step. On a self-hosted installation, MAX_STEP_OUTPUT_BYTES raises that, up to the 64 MB a Code step can return.
  • In a product that embeds GoRunner, the provider’s Code step switch can remove this app.
  • Whole numbers longer than 15 digits lose their last digits. Keep long IDs as text.

Not in your list? See When an app isn’t here.

For developers

In the API, which calls apps pieces, Code is pieceId: "code" with actionId: "run_code". Get an app returns every field.

It computes from its inputs only (pure). See How versions and side effects work.

Code › Run Code

Write JavaScript to transform data. Read mapped values as `inputs.<name>`, earlier steps as `steps.<name>`, and `return` the result.

Inputs · Optional

Name values from earlier steps, such as `email` = `{{trigger.body.email}}`, then read them in the code as `inputs.email`.

Code · Required

JavaScript, run as an async function. Read `inputs.<name>`, `steps.<name>` and `trigger`, then `return` this step's output. No network access: put an HTTP Request step before this one.

Default:

JavaScript
// Read Inputs as inputs.<name>, earlier steps as steps.<name>, the trigger as trigger.
// Whatever you return is this step's result.

const name = inputs.name || "world";

return {
  greeting: `Hello, ${name}!`,
  at: $now,
};