Javascript Copy Object Reference

constructor

// using constructor to clone object
var A = function(){
  this.array = ['a','b','c'];
};

var a = new A();
console.log(a.array);
// ["a", "b", "c"]

var b = new A();
b.array.push('d');
console.log(b.array);
// ["a", "b", "c", "d"]

factory

// using function factory to clone object
var factoryA = function(){
  return ['a','b','c'];
};

var a = factoryA();
console.log(a);
// ["a", "b", "c"]

var b = factoryA();
b.push('d');
console.log(b);
// ["a", "b", "c", "d"]

simple

// most easy way to clone object
var a = ['a','b','c'];
var b = JSON.parse(JSON.stringify(a));
b.push('d');

console.log(a);
// ["a", "b", "c"]
console.log(b);
// ["a", "b", "c", "d"]