n8n-expression-syntax

n8n expressions require double curly braces {{ }} to wrap values. Access webhook data via $json.body, reference other nodes with quoted names like $node["Node Name"].json, and use $now for timestamps and $env for environment variables. Test syntax in the expression editor before running workflows.

Webhook payload arrives under $json.body; root $json contains headers, params, and query separately. Reference body fields as $json.body.fieldName, not $json.fieldName directly. Verify the webhook node name in node references and check data structure in the debugger.

Common errors include missing or mismatched {{ }}, incorrect $json variable paths, unquoted node names with spaces, nested braces, and case-sensitivity mistakes. The Skill covers 15 frequent mistakes with quick fixes and explains when to use code nodes instead of expressions for complex logic.

Reference node output with $node["Node Name"].json for exact names including spaces and case. Access nested fields using dot notation: $json.level1.level2 or bracket notation for dynamic keys. Arrays use index access: $json.array[0].property.

Use expressions for simple variable substitution, field mapping, and date formatting. Switch to code nodes for complex logic, loops, conditional transformations, or when expressions become unreadable. Code nodes support full JavaScript but require manual error handling.

Yes. n8n expressions support array indexing, iteration in code nodes, string methods via JavaScript, and date formatting with $now. The Skill covers typical patterns for arrays, spaces in values, and common string operations within expression syntax constraints.