n8n-code-javascript
Write JavaScript code in n8n Code nodes. Use when writing JavaScript in n8n, using $input/$json/$node syntax, making HTTP requests with $helpers, working with dates using DateTime, troubleshooting Code node errors, choosing between Code node modes, or doing any custom data transformation in n8n. Always use this skill when a workflow needs a Code node — whether for data aggregation, filtering, API calls, format conversion, batch processing logic, or any custom JavaScript. Covers SplitInBatches loop patterns, cross-iteration data, pairedItem, and real-world production patterns.
68
82%
Does it follow best practices?
Impact
—
No eval scenarios have been run
Advisory
Suggest reviewing before use
Quality
Discovery
100%Based on the skill's description, can an agent find and select it at the right time? Clear, specific descriptions lead to better discovery.
This is an excellent skill description that thoroughly covers what the skill does, when to use it, and includes highly specific n8n-related trigger terms. It uses proper third-person voice throughout and provides both broad trigger guidance and specific technical keywords that users would naturally mention. The description is comprehensive without being padded with fluff.
| Dimension | Reasoning | Score |
|---|---|---|
Specificity | Lists multiple specific concrete actions: writing JavaScript in Code nodes, using $input/$json/$node syntax, making HTTP requests with $helpers, working with dates using DateTime, troubleshooting errors, choosing between modes, data aggregation, filtering, API calls, format conversion, batch processing, SplitInBatches loop patterns, cross-iteration data, and pairedItem. | 3 / 3 |
Completeness | Clearly answers both 'what' (write JavaScript in n8n Code nodes, with specific capabilities listed) and 'when' (explicit 'Use when...' clause with multiple trigger scenarios, plus 'Always use this skill when a workflow needs a Code node'). | 3 / 3 |
Trigger Term Quality | Excellent coverage of natural terms users would say: 'n8n', 'Code node', 'JavaScript', '$input', '$json', '$node', '$helpers', 'HTTP requests', 'DateTime', 'SplitInBatches', 'data transformation', 'API calls', 'filtering', 'batch processing'. These are highly specific terms a user working in n8n would naturally use. | 3 / 3 |
Distinctiveness Conflict Risk | Highly distinctive with a clear niche: n8n Code nodes specifically. The n8n-specific syntax references ($input, $json, $node, $helpers, SplitInBatches, pairedItem) make it very unlikely to conflict with general JavaScript or other automation platform skills. | 3 / 3 |
Total | 12 / 12 Passed |
Implementation
64%Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.
This is a solid, highly actionable skill with excellent executable code examples and strong coverage of n8n-specific gotchas (webhook body nesting, pairedItem, SplitInBatches semantics). Its main weaknesses are verbosity — it includes generic JavaScript best practices Claude doesn't need and inlines content that should live in the referenced supporting files — and the lack of explicit validation/verification steps in multi-step workflows. The Production Gotchas section is a standout strength.
Suggestions
Remove or drastically shorten the 'Best Practices' section — items like 'use descriptive variable names', 'prefer array methods', and 'debug with console.log' are generic JS knowledge Claude already has. Keep only n8n-specific best practices (input validation for n8n item format, webhook body checking).
Move the detailed Common Patterns (sections 1-5) and Built-in Functions reference into their respective referenced files (COMMON_PATTERNS.md, BUILTIN_FUNCTIONS.md) and keep only 1-2 brief examples in the main SKILL.md to reduce its length.
Add explicit validation steps to the SplitInBatches workflow pattern, e.g., 'After the loop, verify staticData.results.length matches expected total before proceeding' to create a proper feedback loop for this error-prone pattern.
| Dimension | Reasoning | Score |
|---|---|---|
Conciseness | The skill is fairly comprehensive but includes some unnecessary content: the 'Best Practices' section with advice like 'use descriptive variable names' and 'prefer array methods over loops' is generic JavaScript guidance Claude already knows. The 'Integration with Other Skills' section adds little actionable value. The mode selection guide's checklist format is slightly verbose. However, the core n8n-specific content (webhook body nesting, return format, pairedItem, SplitInBatches gotchas) earns its place. | 2 / 3 |
Actionability | Nearly every section includes executable, copy-paste-ready JavaScript code examples with correct n8n-specific syntax. The examples cover real use cases (aggregation, filtering, HTTP requests, date handling, webhook data access) and show both correct and incorrect patterns with clear ✅/❌ markers. The Production Gotchas section with SplitInBatches and pairedItem patterns is especially actionable. | 3 / 3 |
Workflow Clarity | The skill provides a good deployment checklist and clear mode selection guidance, but lacks explicit validation/verification steps for the workflows described. The SplitInBatches cross-iteration pattern shows a multi-step process (before/inside/after loop) but doesn't include validation checkpoints or error recovery steps. The 'Best Practices' section mentions try-catch but doesn't integrate it into a clear workflow sequence with feedback loops. | 2 / 3 |
Progressive Disclosure | The skill references four supporting files (DATA_ACCESS.md, COMMON_PATTERNS.md, ERROR_PATTERNS.md, BUILTIN_FUNCTIONS.md) with clear signaling, which is good structure. However, no bundle files were provided, so these references are unverifiable. The main SKILL.md itself is quite long (~400+ lines) and includes substantial inline content (full best practices, multiple pattern examples, built-in function reference) that could have been delegated to the referenced files, making the overview leaner. | 2 / 3 |
Total | 9 / 12 Passed |
Validation
90%Checks the skill against the spec for correct structure and formatting. All validation checks must pass before discovery and implementation can be scored.
Validation — 10 / 11 Passed
Validation for skill structure
| Criteria | Description | Result |
|---|---|---|
skill_md_line_count | SKILL.md is long (785 lines); consider splitting into references/ and linking | Warning |
Total | 10 / 11 Passed | |
- Repository
- czlonkowski/n8n-skills
- Commit
27e9d0a
- Reviewed
Table of Contents
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