Node.js vm2 exchanging information between VM and main code using functions

Question

I am using the vm2 module, and I have some code with two functions: get_input() for getting some data that I have, and display() for showing some data, but these functions will not be defined in that code. How do I make some sort of external function that can run the get_input() to give data from an array and output some data to my main code with the display() function? Basically I want to do this:

• Code running in vm2 makes a get_input() call
• Data from an array gets sent to that function
• Data is evaluated with code in the vm2 instance
• vm2 code makes a display() call which outputs data to another array on my main code

Any help would be appreciated.

Answer 1

The sandbox option that you pass into the vm2 constructor represents the "global" object inside the sandbox instance. You can pass functions too:

const { VM } = require('vm2');

const sandbox = {
  get_input(data) {
    return 'input:' + data;
  },
  display(data) {
    console.log('Data:', data);
  }
}

const vm = new VM({ sandbox });

vm.run(`

const array = [ 'foo', 'bar', 'blah' ];

const ret = get_input(array[1]);

display(ret);

`);

(output: Data: input:bar)