# node:vm

> How Elide supports Node's `vm` module: Script, createContext, compileFunction and runIn*Context, and where contexts, code-generation options and modules differ.

`node:vm` provides `Script`, `createContext`, `compileFunction`, `runInContext`, `runInNewContext` and
`runInThisContext` from [Node's `vm`](https://nodejs.org/api/vm.html), including the `timeout` option.

## Example

```js
// vm.mjs
import vm from "node:vm";

const context = vm.createContext({ price: 20, qty: 3 });
console.log(vm.runInContext("price * qty", context));

const script = new vm.Script("count = (typeof count === 'number' ? count : 0) + 1");
script.runInContext(context);
script.runInContext(context);
console.log(context.count);

try {
  vm.runInNewContext("while (true) {}", {}, { timeout: 50 });
} catch (error) {
  console.log(error.code);
}
```

`elide run vm.mjs` prints:

```text
60
2
ERR_SCRIPT_EXECUTION_TIMEOUT
```

## Differences from Node

- A context shares intrinsics (`Symbol`, `Proxy`, `Object`) with the host realm; it is not a security boundary.
- `codeGeneration: { strings: false }` is not enforced; `eval` still runs in the context.
- `vm.constants.DONT_CONTEXTIFY` is rejected by `createContext`.
- `SyntaxError` messages use different wording, such as `Expected eof but found }`.
- `SourceTextModule` emits an `ExperimentalWarning` and does not support full linking and evaluation.

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## Reference

**Status:** Full · 80 of 95 suite tests pass (84.2%) · since 1.1.0

### Exports

| Export | Kind | Status | Notes |
| --- | --- | --- | --- |
| `Script` | class | Full | `runInThisContext()`, `runInNewContext()` |
| `createContext()` | function | Full | Creates a new execution context (sandbox) |
| `runInNewContext()` | function | Full | Compiles code, creates a new context, and runs the code in that context |
| `runInThisContext()` | function | Full | Compiles and runs code within the current global context |
| `isContext()` | function | Full | Returns whether the given object is a contextified sandbox |

**Tests:** [node-api `node:vm`](https://github.com/elide-dev/testsuite/blob/main/reports/1.6.0%2B6e718933f/4cbcae6c33a8/node-api/node-api.md): 80 pass, 15 fail, 0 error, 3 skipped. Failing: `test-vm-basic.js`, `test-vm-codegen.js`, `test-vm-context-dont-contextify.js`, `test-vm-function-declaration.js`, `test-vm-global-property-prototype.js`, `test-vm-global-setter.js`, `test-vm-harmony-symbols.js`, `test-vm-module-after-evaluate.js`, and 7 more.
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