store data in localstorage javascript

var person = { "name": "billy", "age": 23};

localStorage.setItem('person', JSON.stringify(person)); //stringify object and store
var retrievedPerson = JSON.parse(localStorage.getItem('person')); //retrieve the object

localStorage.setItem('user_name', 'Rohit'); //store a key/value
var retrievedUsername = localStorage.getItem('user_name'); //retrieve the key

var testObject = { 'one': 1, 'two': 2, 'three': 3 };

// Put the object into storage
localStorage.setItem('testObject', JSON.stringify(testObject));

// Retrieve the object from storage
var retrievedObject = localStorage.getItem('testObject');

console.log('retrievedObject: ', JSON.parse(retrievedObject));

localStorage.setItem("user_name", "Bob");

document.body.addEventListener("click", function(){
  alert(localStorage.getItem("user_name"))
});