Code (JS Sandbox) Node

6 min readnode-data-code

Run arbitrary JavaScript inside a sandboxed V8 context — transform data, call external APIs, parse JSON, compute values — all from within an automation.

The Code node executes a JavaScript snippet in a sandboxed V8 context. Use it to transform variables, compute derived values, parse JSON from an LLM, or call external APIs that don't have a dedicated node.

> Note: The sandbox has no file system access, no require, and no network access. Use the Webhook node to call external APIs instead, or use fetch which is available inside the sandbox.

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Fields

Field	Type	Required	Description
`code`	string	Yes	JavaScript to execute. Must `return` a value or call `setOutput(key, value)`
`outputVar`	string	No	Variable name to store the return value (default: `codeOutput`)

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Context available inside the sandbox

Name	Type	Description
`variables`	object	All current flow variables (read-only)
`lead`	object	The trigger lead object (read-only)
`flowState`	object	The current `$flow.state` object
`fetch`	function	Standard `fetch` API for HTTP requests
`setOutput`	function	`setOutput(key, value)` — set multiple output variables

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Example: parse JSON from an LLM response

js // variables.llmResponse = '{"score": 8, "reason": "Strong fit"}' const parsed = JSON.parse(variables.llmResponse); setOutput('score', parsed.score); setOutput('reason', parsed.reason); return parsed;

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Example: format a phone number

js const raw = lead.phone || ''; const digits = raw.replace(/\D/g, ''); return digits.startsWith('44') ? '+' + digits : '+44' + digits;

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Example: call an external API

js const res = await fetch('https://api.example.com/score', { method: 'POST', headers: { 'Authorization': 'Bearer ' + variables.apiKey, 'Content-Type': 'application/json' }, body: JSON.stringify({ domain: lead.domain }) }); const data = await res.json(); return data.score;

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Execution limits

Limit	Value
Max execution time	10 seconds
Max output size	100 KB
Memory	64 MB
Network requests	Allowed (via `fetch`)

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Tips

Always return something — if the node returns undefined, outputVar is set to null
Wrap risky code in try/catch and return a fallback value so the automation doesn't halt
Use setOutput when you want to set multiple variables from one code node instead of chaining multiple set_variable nodes