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Evaluating JavaScript

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You can evaluate JavaScript code in a sandbox using the `eval` function. Calling `sandbox.deno.eval()` lets you run arbitrary JavaScript snippets directly inside the sandbox’s Deno runtime without writing files or shelling * out. This is useful when you want to prototype logic, run small computations, or inspect the sandbox environment itself quickly. Use it for dynamic scripts or exploratory debugging where creating a full module would be overkill.

Import the Deno Sandbox SDK
import { Sandbox } from "jsr:@deno/sandbox";
Create a sandbox
await using sandbox = await Sandbox.create();
Run JS in the sandbox with eval
const result = await sandbox.deno.eval(`
  const a = 1;
  const b = 2;
  a + b;
  `);
console.log("result:", result);

Run this example locally using the Deno CLI:

deno run -A https://docs.deno.com/examples/scripts/sandbox_evaluating_javascript.ts

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