Node.js V8 pass by reference

Question

Node.js V8 pass by reference

I am wonder how memory management is done in V8, take a look at this example:

function requestHandler(req, res){
  functionCall(req, res);
  secondFunctionCall(req, res);
  thirdFunctionCall(req, res);
  fourthFunctionCall(req, res);
};

var http = require('http');
var server = http.createServer(requestHandler).listen(3000);

The "req" and "res" variables are passed in every function call, my question is:

Does V8 pass this by reference or does it make a copy in memory? 2. Is it possible to pass variables by reference, look at this example.

var args = { hello: 'world' };

function myFunction(args){
  args.newHello = 'another world';
}

myFunction(args);

console.log(args); // This would print:

"{ hello: 'world', newWorld: 'another world' }"

Thanks for help and answers :)

javascript
node.js
pass-by-reference
v8

Answer 1

That's not what pass by reference means. Pass by reference would mean this:

var args = { hello: 'world' };

function myFunction(args) {
  args = 'hello';
}

myFunction(args);

console.log(args); //"hello"

And the above is not possible.

Variables only contain references to objects, they are not the object themselves. So when you pass a variable that is a reference to an object, that reference will be of course copied. But the object referenced is not copied.

var args = { hello: 'world' };

function myFunction(args){
  args.newHello = 'another world';
}

myFunction(args);
console.log(args); // This would print:
    // "{ hello: 'world', newWorld: 'another world' }"

Yes that's possible and you can see it by simple running the code.