what is the meaning of localstorage in javascript code example

Example 1: local storage javascript

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

Example 2: javascript localstorage

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

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