Module 3 Lesson 3: Power User Nodes

Sometimes, a "Drag and Drop" node isn't enough. You need the full power of a programming language. n8n provides two "Escape Hatches" for engineers: the Code Node and the Execute Command Node.

1. The Code Node (JavaScript/TypeScript)

This is the most powerful node in n8n. It allows you to write a custom function that receives the incoming data and returns a new set of data.

// Example: Converting "ounces" to "grams" for every incoming item
for (const item of $input.all()) {
  item.json.grams = item.json.ounces * 28.3495;
}
return $input.all();

• Why use it?: Complex math, deep JSON manipulation, or integrating custom libraries.

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2. The Execute Command Node (Bash/Shell)

This node runs a command directly on the terminal of your server (or inside your Docker container).

• ls -la: List files in a folder.
• ping google.com: Check connectivity.
• python my_script.py: Trigger a local Python AI script.

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3. Security Warning

These nodes are Dangerous.

• If a hacker gains access to your n8n UI, they can run rm -rf / using the Execute Command node.
• The Fix: n8n disables these by default in many cloud environments. In self-hosted mode, you must enable them with the environment variable N8N_BLOCK_ENV_VARS_IN_CODE=false.

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4. Using External Libraries

You can "Inject" any NPM package into the Code Node.

• Example: Use luxon for advanced date math.
• Set the environment variable: NODE_FUNCTION_ALLOW_EXTERNAL=luxon.

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Exercise: The Scripter's Test

1. Add a Code node. Write a script that takes a field price and adds 20% tax to it.
2. Add an Execute Command node. Run whoami. What user is n8n running as?
3. Try to run python --version. Is Python installed in your n8n container?
4. Why is it better to use a Code node for data processing instead of a chain of 10 Set nodes?
5. Research: What is the "Function Item" node and how does it differ from the main "Code" node?

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Summary

The Code and Execute Command nodes turn n8n from an "Automation tool" into an "Operating System." They allow you to bridge the gap between low-code ease and high-code flexibility.

Next Lesson: Managing the map: Managing Node Connections and Branching.