best way to clone an object in javascript

var x = {myProp: "value"};
var y = Object.assign({}, x); 

var x = {key: 'value'}
var y = JSON.parse(JSON.stringify(x))

//this method actually creates a reference-free version of the object, unlike the other methods
//If you do not use Dates, functions, undefined, regExp or Infinity within your object

var x = {myProp: "value"};
var xClone = Object.assign({}, x);

//Obs: nested objects are still copied as reference.

const person = {
    firstName: 'John',
    lastName: 'Doe'
};


// using spread ...
let p1 = {
    ...person
};

// using  Object.assign() method
let p2 = Object.assign({}, person);

// using JSON
let p3 = JSON.parse(JSON.stringify(person));