how to store data with javascript code example

Example 1: localStorage

// localStorage for objects, arrays or any data type
var obj = {
	firstName: "Bob",
    lastName: "Jeff",
    age: 13
}
localStorage.setItem("itemname", JSON.stringify(obj)); // Save the obj as string
var item = JSON.parse(localStorage.getItem("itemname")); 
// ^^ Parse string then set `item` as the obj

Example 2: javascript localstorage

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

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