The best algorithm for copying objects in Javascript is heavily dependent on the context and type of objects that you are looking to copy

deepClone.js

/*
* 1. 
* objects with properties which are themselves objects, only the references are copied over:
* var foo = { a: 0 , b: { c: 0 } };
* var copy = { ...foo };
*/
var obj = { foo: "foo", bar: "bar" };
var copy = { ...obj };
var copy = Object.assign({}, obj);

/* 
* 2.
* this method only works when the source object contains serializable value types 
* and does not have any circular references 
*/
var obj = { a: 0, b: { c: 0 } };
var copy = JSON.parse(JSON.stringify(obj));

function deepClone(obj) {
  var copy;

  // Handle the 3 simple types, and null or undefined
  if (null == obj || "object" != typeof obj) return obj;

  // Handle Date
  if (obj instanceof Date) {
    copy = new Date();
    copy.setTime(obj.getTime());
    return copy;
  }

  // Handle Array
  if (obj instanceof Array) {
    copy = [];
    for (var i = 0, len = obj.length; i < len; i++) {
        copy[i] = clone(obj[i]);
    }
    return copy;
  }

  // Handle Function
  if (obj instanceof Function) {
    copy = function() {
      return obj.apply(this, arguments);
    }
    return copy;
  }

  // Handle Object
  if (obj instanceof Object) {
      copy = {};
      for (var attr in obj) {
          if (obj.hasOwnProperty(attr)) copy[attr] = clone(obj[attr]);
      }
      return copy;
  }

  throw new Error("Unable to copy obj as type isn't supported " + obj.constructor.name);
}