jsfiddle-console example

https://github.com/eu81273/jsfiddle-console

HTML

<script src="https://cdn.jsdelivr.net/gh/eu81273/jsfiddle-console/console.js"></script>

JavaScript

//https://stackoverflow.com/questions/728360/how-do-i-correctly-clone-a-javascript-object
function deepClone(obj)
{
        var copy;

        // Handle the 3 simple types, and null or undefined
        if (null == obj || "object" != typeof obj) return obj;
    
        // Handle Array
        if (obj instanceof Array) {
            copy = [];
            for (var i = 0, len = obj.length; i < len; i++) {
                copy[i] = deepClone(obj[i]);
            }
            return copy;
        }
    
        // Handle Object
        if (obj instanceof Object) {
            copy = {};
            for (var attr in obj) {
                if (obj.hasOwnProperty(attr)) copy[attr] = deepClone(obj[attr]);
            }
            return copy;
        }
    
        throw new Error("Unable to copy obj! Its type isn't supported.");
}



function A()
{
    this.param1 = {'a': 1};
    this.param2 = 'b';
}

A.prototype.getParam1 = function()
{
    return this.param1;
}

function B(objectToCopyFrom)
{

    //Code to copy all properties from the objectToCopyFrom and inherite prototype.
    Object.assign(this, deepClone(objectToCopyFrom));

    this.param1.a += 2;
    this.param3 = 'c';
}

B.prototype = Object.create(A.prototype);

B.prototype.getParam3 = function()
{
    return this.param3;
}

var a = new A();
a.param1 = {'a': 2};

var b = new B(a);

console.log(b.param3); //Should print: "c"
console.log(JSON.stringify( b.getParam1() )); //Should print: "{'a': 4}"

a.param1.a = 8;

console.log(JSON.stringify( b.getParam1() )); //Still should: "{'a': 4}"