17 Deep copy in JavaScript

deepcopy.js

// You are welcome to have a test on this function to check if it supports deep copy for very complex nested objects.
function deepCopy(o){
  if(typeof o === "object" && o !== null){
    var _o = new o.constructor();
    for(var k in o){
      _o[k] = deepCopy(o[k]);
    }
    return _o;
  }else{
    return o;
  }
}


// test1
var obj = {a: [2,3,4,5]}
var copied = deepCopy(obj);
copied.a.push(2);
console.log(obj);
console.log(copied);
console.log("----");

// test2
var obj = {a: null, b: {}, c:[{d: []}]}
var copied = deepCopy(obj);
copied.c[0].d.push(2);
console.log(obj.c[0]);
console.log(copied.c[0]);
console.log("----");

// test3
var obj = [2,3,[4,5],[6],{a:7},[],{}];
var copied = deepCopy(obj);
copied.push(8);
console.log(obj);
console.log(copied);
console.log("----");

// test4
var obj = {a:{b:{c:1,d:2},e:3}};
var copied = deepCopy(obj);
copied.a.e = 4;
console.log(obj);
console.log(copied);
console.log("----");

// test5
var obj = 2;
var copied = deepCopy(obj);
copied = 4;
console.log(obj);
console.log(copied);
console.log("----");