Use native node:vm modue when available

Author: petebacondarwin

.changeset/upset-ducks-sin.md

@@ -0,0 +1,5 @@
+---
+"@cloudflare/unenv-preset": patch
+---
+
+Use native node:vm module when available

packages/unenv-preset/src/preset.ts

@@ -72,6 +72,7 @@ export function getCloudflarePreset({
 	const http2Overrides = getHttp2Overrides(compat);
 	const osOverrides = getOsOverrides(compat);
 	const fsOverrides = getFsOverrides(compat);
+	const vmOverrides = getVmOverrides(compat);
 
 	// "dynamic" as they depend on the compatibility date and flags
 	const dynamicNativeModules = [
@@ -80,6 +81,7 @@ export function getCloudflarePreset({
 		...http2Overrides.nativeModules,
 		...osOverrides.nativeModules,
 		...fsOverrides.nativeModules,
+		...vmOverrides.nativeModules,
 	];
 
 	// "dynamic" as they depend on the compatibility date and flags
@@ -89,6 +91,7 @@ export function getCloudflarePreset({
 		...http2Overrides.hybridModules,
 		...osOverrides.hybridModules,
 		...fsOverrides.hybridModules,
+		...vmOverrides.hybridModules,
 	];
 
 	return {
@@ -305,3 +308,39 @@ function getFsOverrides({
 				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

@@ -188,6 +188,34 @@ const testConfigs: TestConfig[] = [
 			},
 		},
 	],
+	// node:vm
+	[
+		{
+			name: "vm disabled by date",
+			compatibilityDate: "2024-09-23",
+			expectRuntimeFlags: {
+				enable_nodejs_vm_module: false,
+			},
+		},
+		// TODO: add a config when vm is enabled by default (>= 2025-10-01)
+		{
+			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",
+			// TODO: change the date passed the default enabled date (>= 2025-10-01)
+			compatibilityDate: "2025-07-26",
+			compatibilityFlags: ["disable_nodejs_vm_module"],
+			expectRuntimeFlags: {
+				enable_nodejs_vm_module: false,
+			},
+		},
+	],
 ].flat() as TestConfig[];
 
 describe.each(testConfigs)(

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

@@ -505,4 +505,64 @@ export const WorkerdTests: Record<string, () => void> = {
 		assert.strictEqual(typeof http2.connect, "function");
 		assert.strictEqual(http2.constants.HTTP2_HEADER_STATUS, ":status");
 	},
+
+	async testVm() {
+		const vm = await import("node:vm");
+
+		assertType(vm.Script, "function", "vm.Script");
+		assertType(vm.constants, "object", "vm.constants");
+		assertType(vm.compileFunction, "function", "vm.compileFunction");
+		assertType(vm.createContext, "function", "vm.createContext");
+		// @ts-expect-error undocumented API
+		assertType(vm.createScript, "function", "vm.createScript");
+		assertType(vm.isContext, "function", "vm.isContext");
+		assertType(vm.measureMemory, "function", "vm.measureMemory");
+		assertType(vm.runInContext, "function", "vm.runInContext");
+		assertType(vm.runInThisContext, "function", "vm.runInThisContext");
+		assertType(vm.runInNewContext, "function", "vm.runInNewContext");
+
+		assertType(vm.default.Script, "function", "vm.default.Script");
+		assertType(
+			vm.default.compileFunction,
+			"function",
+			"vm.default.compileFunction"
+		);
+		assertType(vm.default.constants, "object", "vm.default.constants");
+		assertType(
+			vm.default.createContext,
+			"function",
+			"vm.default.createContext"
+		);
+		assertType(vm.default.isContext, "function", "vm.default.isContext");
+		assertType(
+			vm.default.measureMemory,
+			"function",
+			"vm.default.measureMemory"
+		);
+		assertType(vm.default.runInContext, "function", "vm.default.runInContext");
+		assertType(
+			vm.default.runInNewContext,
+			"function",
+			"vm.default.runInNewContext"
+		);
+		assertType(
+			vm.default.runInThisContext,
+			"function",
+			"vm.default.runInThisContext"
+		);
+		assertType(
+			// @ts-expect-error undocumented API
+			vm.default.createScript,
+			"function",
+			"vm.default.createScript"
+		);
+	},
 };
+
+function assertType(value: unknown, type: string, name: string) {
+	assert.strictEqual(
+		typeof value,
+		type,
+		`Expected ${name} to be of type ${type}, but got ${typeof value}`
+	);
+}