String constructor - how can i pass?

JavaScript
2

What you did here is wrong,instead,you have two options:
1)(The regular way):
Pass a variable and return it:

function helloWorld(str){
  str="hello world"
  return str;
}
let hw=helloWorld(hw);
console.log(hw); //prints hello world
  1. pass a object to a function and get 2 fields (hello,world) inside the object (note: This might override another values,if the fields hello or world already exists inside the passed object)
function helloWorld(a){
  a.hello="hello";
  a.world="world";
}
let hw={};
helloWorld(hw);
console.log(hw.hello+" "+hw.world); // prints hello world