CopyObject.js

function copy(obj) {
    var copy = Object.create(Object.getPrototypeOf(obj));
    var propNames = Object.getOwnPropertyNames(obj);

    propNames.forEach(function (name) {
        var desc = Object.getOwnPropertyDescriptor(obj, name);
        Object.defineProperty(copy, name, desc);
    });

    return copy;
}

// Object test
var obj1 = { a: 1, b: 2 };
var obj2 = copy(obj1);
// obj2 looks like obj1 now


// Array test
var arr = []
var arr1 = [1, 2, arr]
var arr2 = copy(arr1)

// Shalow copy test
arr2.push(2) // => only affect arr2

// Deep copy test
arr.push(1) // => affecting both arr1 and arr2