JSFiddle - React, Tailwind, and code Playground

HTML

<button id="add" onclick="localStorage.setItem('a','test')">Add</button>
<button id="clear" onclick="localStorage.clear()">Clear</button>

JavaScript

var focused;

      window.addEventListener('focus', function(){focused=1;}, false);
      window.addEventListener('blur', function(){focused=0;}, false);

      var handle_storage = function (e) {
        if(!focused)
          alert("Storage",focused);
      };

      window.addEventListener("storage", handle_storage, false);