how to automatically get local storage from document when opening a document code example

Example 1: local storage

function setItem(name, value) {
  localStorage.setItem(name, value);
}
function getItem(name) {
  localStorage.getItem(name);
}
function deletItem(name) {
  localStorage.removeItem(name);
}
function clearStorage() {
  localStorage.clear();
}

Example 2: javascript localstorage

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

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