NodeJS VM2 proper way to access console when set to 'redirect' - node.js

Question

I'm using the VM2 package to run user code. I'm trying to intercept console output and have set the NodeVM object's console property to 'redirect':
// Create a new sandbox VM for this request
const vm = new NodeVM( {
console: 'redirect',
timeout: 30000,
sandbox: { request, state, response },
require: {
external: true
}
});
According to the documentation that redirects console output to 'events'. I'm new to NodeJS, how do I hook into those events to capture the console.log messages executed inside the Sandbox?

Answer 1

After digging through the source code, I found this file where the event emit is occuring:
sandbox.js
if (vm.options.console === 'inherit') {
global.console = Contextify.readonly(host.console);
} else if (vm.options.console === 'redirect') {
global.console = {
log(...args) {
vm.emit('console.log', ...Decontextify.arguments(args));
return null;
},
info(...args) {
vm.emit('console.info', ...Decontextify.arguments(args));
return null;
},
warn(...args) {
vm.emit('console.warn', ...Decontextify.arguments(args));
return null;
},
error(...args) {
vm.emit('console.error', ...Decontextify.arguments(args));
return null;
},
dir(...args) {
vm.emit('console.dir', ...Decontextify.arguments(args));
return null;
},
time: () => {},
timeEnd: () => {},
trace(...args) {
vm.emit('console.trace', ...Decontextify.arguments(args));
return null;
}
};
}
All you need to do to listen to these events is to bind an event listener on the vm you've created:
// Create a new sandbox VM for this request
const vm = new NodeVM( {
console: 'redirect',
require: {
external: ['request']
}
});
vm.on('console.log', (data) => {
console.log(`VM stdout: ${data}`);
});
Likewise, you can bind to console.log, console.info, console.warn, console.error, console.dir, and console.trace. Hopefully this will save someone else some time.