A bug about vm module

[xiaotiananan]

Version

18.4.1

Platform

No response

Subsystem

vm

What steps will reproduce the bug?

const vm = require('vm');
// Constructing context
var contextobj = { globalVar:6 };
// Contextifying object
vm.createContext(contextobj);
// Calling for loop
const script = new vm.Script(`console.log(this.hasOwnProperty("hasOwnProperty"))`);
// Calling runInContext method
script.runInContext(contextobj);

"The console should output false, but the result is true"

How often does it reproduce? Is there a required condition?

always

What is the expected behavior?

The console should output false, but the result is true

What do you see instead?

The console output true

Additional information

No response

[bnoordhuis]

The console should output false, but the result is true

Can you elaborate why you expect that?

[xiaotiananan]

The console should output false, but the result is true

Can you elaborate why you expect that?

Because the output is false in the browser environment and false in the v8 environment, but true in the vm environment

[koshic]

@xiaotiananan if you want to see false, just call script.runInThisContext(); - you are using the wrong context and getting the wrong results

[bnoordhuis]

@koshic has it right. Closing as not a bug, can convert to a discussion if needed (edit: done)

[xiaotiananan]

@xiaotiananan if you want to see false, just call script.runInThisContext(); - you are using the wrong context and getting the wrong results

If I want to create a new context to execute the script, what should I do. My purpose is not to execute the script in the current context. Why can't we get the same results in the new context as in the browser environment.

[koshic]

@xiaotiananan if you want to see false, just call script.runInThisContext(); - you are using the wrong context and getting the wrong results

If I want to create a new context to execute the script, what should I do. My purpose is not to execute the script in the current context. Why can't we get the same results in the new context as in the browser environment.

These are 2 different questions: how can you solve your problem and why VM module doesn't have methods to create context objects very close to node / browser global context.

I can't answer #2, so if you want - you can describe your setup & requirements a bit more and we can try to find alternative way (child process / fork as an example).