JSFiddle - React, Tailwind, and code Playground

JavaScript

var num = 10;
var obj1 = {item:"unchanged"};
var obj2 = {item:"unchanged"};

document.write("before");
document.write("<br/>");
document.write(num);
document.write("<br/>");
document.write(obj1.item);
document.write("<br/>");
document.write(obj2.item);

function changer(primitive, objA, objB){
    primitive = primitive*10;
    objA.item = "changed";
    objB = {item:"changed"};    
}

changer(num, obj1, obj2);
document.write("<br/>");

document.write("after");
document.write("<br/>");
document.write(num);
document.write("<br/>");
document.write(obj1.item);
document.write("<br/>");
document.write(obj2.item);