Node.js VM Module

Here is a complete, clean, and easy-to-understand Node.js VM Module tutorial — perfect for your Node.js documentation series.

🚀 Node.js VM Module Tutorial

The VM (Virtual Machine) Module in Node.js allows you to:

✔ Run JavaScript code safely in sandboxes
✔ Execute untrusted code
✔ Create isolated contexts
✔ Build custom scripting engines
✔ Implement template engines
✔ Run code with controlled permissions

Built-in import:

The VM module is powerful but must be used carefully.

🧠 What is the VM Module?

The VM module lets you run JavaScript code inside:

Isolated contexts (sandbox)
New global scopes
Controlled environments
Virtualized V8 contexts

This is similar to eval() but much safer and more controlled.

🌐 1. Basic Example: Run Code in VM

🔒 2. Run Code in a Sandbox (Isolated Global)

Example with sandbox:

The code runs only inside sandbox, not in Node.js global scope.

🧱 3. Fully Isolated Execution

🕒 4. Run Code with Timeout or Memory Limit

Prevent infinite loops:

Prevent heavy memory usage:

🧩 5. vm.Script() — Precompiled Code

Useful when reusing same code multiple times.

const vm = require("node:vm");

const script = new vm.Script("value += 1");

const context = { value: 10 };
vm.createContext(context);

for (let i = 0; i < 5; i++) {
script.runInContext(context);
}

console.log(context.value); // 15

const vm = require("node:vm");

const script = new vm.Script("value += 1");

const context = { value: 10 };

vm.createContext(context);

for (let i = 0; i < 5; i++) {

script.runInContext(context);

}

console.log(context.value); // 15

🌐 6. Using runInNewContext()

Creates a brand new sandbox every time.

📦 7. Accessing Node.js in VM (Controlled)

You can expose only selected APIs:

By default, Node.js Globals are NOT exposed inside VM.

🚫 8. Prevent Access to Dangerous APIs

Restricting sandbox:

🧪 9. Using VM to Execute Dynamic User Code

const vm = require("node:vm");

function runUserCode(code) {
const sandbox = { result: null };
vm.createContext(sandbox);

try {
vm.runInContext(code, sandbox, { timeout: 200 });
return sandbox.result;
} catch (error) {
return "Error: " + error.message;
}
}

console.log(runUserCode("result = 5 * 5"));

const vm = require("node:vm");

function runUserCode(code) {

const sandbox = { result: null };

vm.createContext(sandbox);

try {

vm.runInContext(code, sandbox, { timeout: 200 });

return sandbox.result;

} catch (error) {

return "Error: " + error.message;

}

console.log(runUserCode("result = 5 * 5"));

🪟 10. vm.SourceTextModule – ES Module Support

Node.js VM supports ES module evaluation.

const vm = require("node:vm");

(async () => {
const module = new vm.SourceTextModule(`
export const add = (a, b) => a + b;
`);

await module.link(() => {});
await module.evaluate();

console.log(module.namespace.add(5, 3)); // 8
})();

const vm = require("node:vm");

(async () => {

const module = new vm.SourceTextModule(`

export const add = (a, b) => a + b;

`);

await module.link(() => {});

await module.evaluate();

console.log(module.namespace.add(5, 3)); // 8

})();

⚙️ 11. vm.Module — Advanced Module Loading

Used to create custom loaders.

📘 12. Summary of VM Module Features

Feature	Description
`runInNewContext`	Run code in isolated sandbox
`runInContext`	Reuse existing sandbox
`runInThisContext`	Run in same global but isolated
`vm.Script`	Precompile and reuse JS code
`vm.createContext`	Create a sandbox
`vm.Module`	Create ES modules
`timeout`	Restrict runtime
`cachedData`	Speed up script execution

🛡️ 13. When to Use VM Module

✔ Running untrusted code safely
✔ Sandboxed user scripting
✔ Custom JS engines
✔ Template engines
✔ Serverless-like environments
✔ Testing snippets
✔ Security-sensitive applications

🎉 Conclusion

Node.js VM Module is extremely powerful for:

Isolation
Security
Performance
Sandbox environments
Dynamic code evaluation

You can build advanced systems like:

Online code editors
Template engines
Automation tools
Custom interpreters

Node.js VM Module

🚀 Node.js VM Module Tutorial

🧠 What is the VM Module?

🌐 1. Basic Example: Run Code in VM

🔒 2. Run Code in a Sandbox (Isolated Global)

Example with sandbox:

🧱 3. Fully Isolated Execution

🕒 4. Run Code with Timeout or Memory Limit

🧩 5. vm.Script() — Precompiled Code

🌐 6. Using runInNewContext()

📦 7. Accessing Node.js in VM (Controlled)

🚫 8. Prevent Access to Dangerous APIs

🧪 9. Using VM to Execute Dynamic User Code

🪟 10. vm.SourceTextModule – ES Module Support

⚙️ 11. vm.Module — Advanced Module Loading

📘 12. Summary of VM Module Features

🛡️ 13. When to Use VM Module

🎉 Conclusion

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Node.js VM Module

🚀 Node.js VM Module Tutorial

🧠 What is the VM Module?

🌐 1. Basic Example: Run Code in VM

🔒 2. Run Code in a Sandbox (Isolated Global)

Example with sandbox:

🧱 3. Fully Isolated Execution

🕒 4. Run Code with Timeout or Memory Limit

🧩 5. vm.Script() — Precompiled Code

🌐 6. Using runInNewContext()

📦 7. Accessing Node.js in VM (Controlled)

🚫 8. Prevent Access to Dangerous APIs

🧪 9. Using VM to Execute Dynamic User Code

🪟 10. vm.SourceTextModule – ES Module Support

⚙️ 11. vm.Module — Advanced Module Loading

📘 12. Summary of VM Module Features

🛡️ 13. When to Use VM Module

🎉 Conclusion

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