Use native node:vm module when available

Author: petebacondarwin

.changeset/upset-ducks-sin.md

@@ -0,0 +1,7 @@
+---
+"@cloudflare/unenv-preset": patch
+---
+
+Use native node:vm module when available
+
+It is enabled starting on 2025-10-01 or when the `enable_nodejs_vm_module` compatibility flag is set.

packages/unenv-preset/src/preset.ts

@@ -77,6 +77,7 @@ export function getCloudflarePreset({
 	const traceEventsOverrides = getTraceEventsOverrides(compat);
 	const domainOverrides = getDomainOverrides(compat);
 	const wasiOverrides = getWasiOverrides(compat);
+	const vmOverrides = getVmOverrides(compat);
 
 	// "dynamic" as they depend on the compatibility date and flags
 	const dynamicNativeModules = [
@@ -90,6 +91,7 @@ export function getCloudflarePreset({
 		...traceEventsOverrides.nativeModules,
 		...domainOverrides.nativeModules,
 		...wasiOverrides.nativeModules,
+		...vmOverrides.nativeModules,
 	];
 
 	// "dynamic" as they depend on the compatibility date and flags
@@ -104,6 +106,7 @@ export function getCloudflarePreset({
 		...traceEventsOverrides.hybridModules,
 		...domainOverrides.hybridModules,
 		...wasiOverrides.hybridModules,
+		...vmOverrides.hybridModules,
 	];
 
 	return {
@@ -510,3 +513,39 @@ function getWasiOverrides({
 				hybridModules: [],
 			};
 }
+
+/**
+ * Returns the overrides for `node:vm` (unenv or workerd)
+ *
+ * The native vm implementation:
+ * - is enabled starting from 2025-10-01
+ * - can be enabled with the "enable_nodejs_vm_module" flag
+ * - can be disabled with the "disable_nodejs_vm_module" flag
+ */
+function getVmOverrides({
+	compatibilityDate,
+	compatibilityFlags,
+}: {
+	compatibilityDate: string;
+	compatibilityFlags: string[];
+}): { nativeModules: string[]; hybridModules: string[] } {
+	const disabledByFlag = compatibilityFlags.includes(
+		"disable_nodejs_vm_module"
+	);
+
+	const enabledByFlag = compatibilityFlags.includes("enable_nodejs_vm_module");
+	const enabledByDate = compatibilityDate >= "2025-10-01";
+
+	const enabled = (enabledByFlag || enabledByDate) && !disabledByFlag;
+
+	// The native `vm` module implements all the node APIs so we can use it directly
+	return enabled
+		? {
+				nativeModules: ["vm"],
+				hybridModules: [],
+			}
+		: {
+				nativeModules: [],
+				hybridModules: [],
+			};
+}

packages/wrangler/e2e/unenv-preset/preset.test.ts

@@ -347,6 +347,39 @@ const localTestConfigs: TestConfig[] = [
 			},
 		},
 	],
+	// node:vm
+	[
+		{
+			name: "vm disabled by date",
+			compatibilityDate: "2024-09-23",
+			expectRuntimeFlags: {
+				enable_nodejs_vm_module: false,
+			},
+		},
+		{
+			name: "vm enabled by date",
+			compatibilityDate: "2025-10-01",
+			expectRuntimeFlags: {
+				enable_nodejs_vm_module: true,
+			},
+		},
+		{
+			name: "vm enabled by flag",
+			compatibilityDate: "2024-09-23",
+			compatibilityFlags: ["enable_nodejs_vm_module"],
+			expectRuntimeFlags: {
+				enable_nodejs_vm_module: true,
+			},
+		},
+		{
+			name: "vm disabled by flag",
+			compatibilityDate: "2025-10-01",
+			compatibilityFlags: ["disable_nodejs_vm_module"],
+			expectRuntimeFlags: {
+				enable_nodejs_vm_module: false,
+			},
+		},
+	],
 ].flat() as TestConfig[];
 
 describe.each(localTestConfigs)(

packages/wrangler/e2e/unenv-preset/worker/index.ts

@@ -645,6 +645,36 @@ export const WorkerdTests: Record<string, () => void> = {
 			/not implemented/
 		);
 	},
+
+	async testVm() {
+		const vm = await import("node:vm");
+
+		assertTypeOfProperties(vm, {
+			Script: "function",
+			constants: "object",
+			compileFunction: "function",
+			createContext: "function",
+			createScript: "function",
+			isContext: "function",
+			measureMemory: "function",
+			runInContext: "function",
+			runInThisContext: "function",
+			runInNewContext: "function",
+		});
+
+		assertTypeOfProperties(vm.default, {
+			Script: "function",
+			compileFunction: "function",
+			constants: "object",
+			createContext: "function",
+			isContext: "function",
+			measureMemory: "function",
+			runInContext: "function",
+			runInNewContext: "function",
+			runInThisContext: "function",
+			createScript: "function",
+		});
+	},
 };
 
 /**