JSFiddle - React, Tailwind, and code Playground

HTML

Look in the console. Hit refresh to increase the number of users.

JavaScript

(function() { // Scoping function to avoid creating globals
	// Loading
	var users = JSON.parse(localStorage.getItem("users") || "[]");
  console.log("# of users: " + users.length);
  users.forEach(function(user, index) {
  	console.log("[" + index + "]: " + user.id);
  });
  
  // Modifying
  var user = {
  	id: Math.floor(Math.random() * 1000000)
  };
  users.push(user);
  console.log("Added user #" + user.id);

	// Saving
  localStorage.setItem("users", JSON.stringify(users));
})();