simple javascript caching using localStorage and a time to live (TTL)

cache.js

var cache = function() {
  var store = window.localStorage;
  
  return {
       set: function(key, value, ttl){
        var time = new Date(); 
        time.setTime(time.getTime() + ttl); 
        store.setItem(key, JSON.stringify({
          ttl: time.getTime(),
          content: value
        }));
      },
      get: function(key){
        var data = store.getItem(key);

        if (!data){
          return null;
        }
       
        var entry = JSON.parse(data); 
        var now = new Date().getTime();
        
        if( now > entry.ttl ){
          this.remove(key);
        }
        return entry;
      },
      remove: function(key){
        store.removeItem(key);
      },
      clear: function(){
        store.clear();
      }
   };
}

var layer = cache();

layer.set("test1", {"hallo" : "lorem ipsum"}, 1000 * 10);

window.setInterval(function() {
 console.log(layer.get("test1"));
}, 1000);