How to Use the Code Node in n8n for Custom JavaScript and Python

1// JavaScript — basic data transformation
2const items = $input.all();
3
4const results = items.map(item => {
5  return {
6    json: {
7      fullName: `${item.json.firstName} ${item.json.lastName}`,
8      email: item.json.email.toLowerCase(),
9      isActive: item.json.status === 'active',
10      processedAt: new Date().toISOString()
11    }
12  };
13});
14
15return results;

1# Python — basic data transformation
2items = []
3
4for item in _input.all():
5    data = item.json
6    items.append({
7        "json": {
8            "fullName": f"{data['firstName']} {data['lastName']}",
9            "email": data["email"].lower(),
10            "isActive": data["status"] == "active",
11            "wordCount": len(data.get("description", "").split())
12        }
13    })
14
15return items

1// Run Once for All Items mode — aggregate example
2const items = $input.all();
3
4const total = items.reduce(
5  (sum, item) => sum + item.json.amount,
6  0
7);
8
9return [{
10  json: {
11    totalAmount: total,
12    itemCount: items.length,
13    average: total / items.length
14  }
15}];
16
17// ---
18
19// Run Once for Each Item mode — per-item example
20// $input.item is the current item
21const data = $input.item.json;
22
23return [{
24  json: {
25    ...data,
26    taxAmount: data.price * 0.08,
27    totalWithTax: data.price * 1.08
28  }
29}];

1// Reference another node's output
2const webhookData = $('Webhook').first().json;
3const apiResponse = $('HTTP Request').all();
4
5// Access environment variables
6const apiKey = $env.API_KEY;
7const baseUrl = $env.BASE_URL;
8
9// Use static data for persistence between runs
10const staticData = $getWorkflowStaticData('global');
11staticData.lastRun = new Date().toISOString();
12
13// Get execution metadata
14const executionId = $execution.id;
15const workflowId = $workflow.id;
16
17return [{
18  json: {
19    webhookBody: webhookData.body,
20    apiItemCount: apiResponse.length,
21    environment: baseUrl,
22    executionId,
23    workflowId
24  }
25}];

1const items = $input.all();
2const results = [];
3const errors = [];
4
5for (const item of items) {
6  try {
7    // Process item — may fail for some items
8    const parsed = JSON.parse(item.json.rawData);
9    results.push({
10      json: {
11        id: item.json.id,
12        parsed,
13        status: 'success'
14      }
15    });
16  } catch (error) {
17    errors.push({
18      json: {
19        id: item.json.id,
20        error: error.message,
21        status: 'failed'
22      }
23    });
24  }
25}
26
27// Return both successes and errors
28return [...results, ...errors];