n8n-code-javascript

Topics in the source

• JavaScript Code Node
• Quick Start
• Essential Rules
• Mode Selection Guide
• Run Once for All Items (Recommended - Default)
• Run Once for Each Item
• Data Access Patterns
• Pattern 1: $input.all() - Most Common

Expert guidance for writing JavaScript code in n8n Code nodes. -- 1. Choose "Run Once for All Items" mode (recommended for most use cases) 2. Access data: $input.all(), $input.first(), or $input.item 3. CRITICAL: Must return [{json: {...}}] format 4. CRITICAL: Webhook data is under $json.body (not $json directly) 5. Built-ins available: $helpers.httpRequest(), DateTime (Luxon), $jmespath() -- The Code node offers two execution modes. Choose based on your use case: Use this mode for: 95% of use cases How it works: Code executes once regardless of input count Data access: $input.all() or items array Best for: Aggregation, filtering, batch processing, transformations, API calls with all data Performance: Faster for multiple items (single execution) When to use: ✅ Comparing items across the dataset ✅ Calculating totals, averages, or statistics ✅ Sorting or ranking items ✅ Deduplication ✅ Building aggregated reports ✅ Combining data from multiple items Use this mode for: Specialized cases only How it works: Code executes separately for each input item Data access: $input.item or $item Best for: Item-specific logic, independent operations, per-item validation Performance: Slower for larg

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