> ## Documentation Index > Fetch the complete documentation index at: https://docs.rovax.io/llms.txt > Use this file to discover all available pages before exploring further. # JavaScript Code Node > Run custom JavaScript in an isolated runtime to transform, validate, or combine data within the workflow. ## What It Does The **JavaScript Code** node executes a JS snippet in an isolated environment with no access to the network or file system. Use it when data transformations become too complex for `{{ }}` expressions, or when you need conditional logic, iteration, or string manipulation that other nodes do not cover natively. Typical use cases: * Transform the structure of a JSON returned by an external API * Validate fields and throw descriptive errors when data is missing * Calculate derived values (discount, due date, hash) * Combine data from multiple upstream nodes into a single object * Format strings: masked IDs, localized dates, URL slugs *** ## Input and Output **Variables available in the code scope:** | Variable | Type | Description | | --------- | -------- | ----------------------------------------------------------- | | `input` | `any` | Output of the immediately preceding node (`$json`) | | `trigger` | `object` | Full trigger payload (`body`, `headers`, `query`, `method`) | | `vars` | `object` | Workflow variables defined by Set Variable nodes | **Output:** the value returned via `return` is exposed as `$json` to downstream nodes. It can be an object, array, string, number, or boolean. *** ## Configuration In the component palette, select **Actions > JavaScript Code** and drag it onto the canvas. The editor accepts modern JavaScript (ES2020+). Use `return` to define the node's output. Auto-generated starter template: ```javascript theme={null} // Access input data via 'input' // Return the result with 'return' const data = input; const result = { processed: true, original: data, timestamp: new Date().toISOString() }; return result; ``` Do not use `{{ }}` expressions inside JS code — access data through the global variables: ```javascript theme={null} // Correct const nome = trigger.body.cliente.nome; const plano = vars.plano_selecionado; // Incorrect — {{ }} is not interpolated inside the JS editor const nome = "{{ $trigger.body.cliente.nome }}"; ``` `console.log()` is available and logs appear in the node's execution panel during tests. In production, logs are discarded. Click **Test** in the node panel. The runtime executes the code with the pinned output data from upstream nodes and displays the result and execution duration. *** ## Available APIs The runtime is isolated — there is no access to the network, file system, or environment variables. The available JavaScript APIs are: | API | Available | | ----------------------------------- | ---------------- | | `JSON.parse()` / `JSON.stringify()` | yes | | `Math.*` | yes | | `Date` | yes | | `RegExp` | yes | | `Array.*` / `Object.*` / `String.*` | yes | | `console.log()` | yes (debug only) | | `fetch()` / `XMLHttpRequest` | no | | `fs` / `path` / Node.js modules | no | | `setTimeout` / `setInterval` | no | | `require()` / `import` | no | *** ## Examples ### Transform API response structure The external API returns a format different from what downstream nodes expect. ```json Input (input — output of the preceding HTTP node) theme={null} { "status": 200, "body": { "data": { "customer_id": "C-4821", "full_name": "Ana Lima", "contact_email": "ana@empresa.com", "is_premium": true, "created_at": "2025-01-15T10:30:00Z" } } } ``` ```javascript Code theme={null} const raw = input.body.data; return { id: raw.customer_id, nome: raw.full_name, email: raw.contact_email, premium: raw.is_premium, membro_desde: new Date(raw.created_at).toLocaleDateString('pt-BR') }; ``` ```json Node output ($json) theme={null} { "id": "C-4821", "nome": "Ana Lima", "email": "ana@empresa.com", "premium": true, "membro_desde": "15/01/2025" } ``` *** ### Format and validate a CPF ```javascript Code theme={null} const cpfRaw = trigger.body.cpf || ''; const numeros = cpfRaw.replace(/\D/g, ''); if (numeros.length !== 11) { return { valido: false, cpf: null, erro: 'CPF deve ter 11 dígitos' }; } const cpfFormatado = numeros.replace( /(\d{3})(\d{3})(\d{3})(\d{2})/, '$1.$2.$3-$4' ); return { valido: true, cpf: cpfFormatado, erro: null }; ``` ```json Output — valid CPF theme={null} { "valido": true, "cpf": "123.456.789-09", "erro": null } ``` ```json Output — invalid CPF theme={null} { "valido": false, "cpf": null, "erro": "CPF deve ter 11 dígitos" } ``` The downstream Condition node checks `{{ $json.valido }}` and routes to the error path when `false`. *** ### Calculate a due date ```javascript Code theme={null} const diasParaVencer = vars.prazo_dias || 30; const hoje = new Date(); hoje.setDate(hoje.getDate() + Number(diasParaVencer)); return { vencimento_iso: hoje.toISOString().split('T')[0], vencimento_br: hoje.toLocaleDateString('pt-BR'), dias_restantes: Number(diasParaVencer) }; ``` ```json Output theme={null} { "vencimento_iso": "2026-05-19", "vencimento_br": "19/05/2026", "dias_restantes": 30 } ``` *** ### Combine data from multiple nodes When you need to assemble an object with fields coming from different nodes (HTTP, LLM, and trigger), use the JavaScript node as a consolidation point before sending. ```javascript theme={null} // Data from the trigger const cliente = trigger.body.cliente; // Output of the HTTP node (saved to a variable via Set Variable node) const pedido = vars.dados_pedido; // Output of the LLM node (output of the preceding node) const classificacao = input.result; return { cliente_nome: cliente.nome, cliente_email: cliente.email, pedido_id: pedido.id, pedido_valor: pedido.valor, intencao: classificacao.intencao, prioridade: classificacao.confianca > 0.8 ? 'alta' : 'normal', gerado_em: new Date().toISOString() }; ``` *** ### Filter and sort an array ```javascript Code theme={null} const itens = input.body.itens || []; const ativos = itens .filter(item => item.ativo === true) .sort((a, b) => b.valor - a.valor) .slice(0, 5); return { total_recebidos: itens.length, total_ativos: ativos.length, top5: ativos }; ``` ```json Output theme={null} { "total_recebidos": 42, "total_ativos": 18, "top5": [ { "id": "P-01", "nome": "Produto A", "valor": 499.90, "ativo": true }, { "id": "P-07", "nome": "Produto B", "valor": 399.00, "ativo": true } ] } ``` *** ## Error Handling If the code throws an uncaught exception, the node marks the execution as failed and the error appears in the execution logs. To handle errors in a controlled way, use `try/catch`: ```javascript theme={null} try { const dados = JSON.parse(trigger.body.payload_raw); return { sucesso: true, dados }; } catch (err) { return { sucesso: false, erro: err.message, dados: null }; } ``` *** ## Limits | Parameter | Value | | ------------------------------ | ------------------- | | Execution timeout | 10 seconds | | Network access | Not allowed | | File system access | Not allowed | | `require()` / external modules | Not supported | | Maximum script size | No documented limit | | Maximum output size | 10 MB | Infinite loops or very heavy synchronous operations cause a timeout after 10 seconds. Prefer array processing with `Array.map()` and `Array.filter()` instead of `while` loops without a clear exit condition. *** ## Next Steps * [Variables Node](/en/guides/workflows/nodes/variables) — store the code output for use in multiple nodes * [LLM Node](/en/guides/workflows/nodes/llm) — use AI before JavaScript to extract unstructured data * [HTTP Request Node](/en/guides/workflows/nodes/http) — send the object built by JavaScript to an external API * [Nodes overview](/en/guides/workflows/nodes/overview) — see all available node types