title: how to delete indexedDB after 2 hours or less using timestamp Dexie.js instead of date search
body: <p>Am using <code>Dexie.js</code> on my website to cache ajax response, but i would love to delete some old cache after 5 minites or more depending on the useage.
  So mu question is how do i delete cached data using time not date.</p>
  
  <p>Saving to cache indexedDB</p>
  
  <pre><code>function getTodayDate(){
      var today = new Date();
      var dd = today.getDate();
      var mm = today.getMonth()+1; 
      var yyyy = today.getFullYear();
      if(dd&lt;10) {dd = '0'+dd} 
      if(mm&lt;10) {mm = '0'+mm} 
      return  mm + '-' + dd + '-' + yyyy;
  }
  
  var time = new Date().getTime();
  db.product.put({nameId: "abc163", text: "hello world", cacheUrl: "example.com", timestamp: time, date: getTodayDate()})
  .catch(function(error) {
       console.log ("Ooops: " + error);
  });
  </code></pre>
  
  <p>Here is how i delete using date search</p>
  
  <pre><code>db.product.where("date").below(getTodayDate()).delete()
  .then(function (deleteCount) {
      console.log( "Deleted " + deleteCount + " objects");
  });
  </code></pre>
  
  <p>But i what to delete by time maybe after 1 hour, 60 hours or less, i don't know if is possible but i think it can be done.</p>
  
  <pre><code>function checkTime(){
      var delete_after = 300;
      //How do i check it
  }
  
  db.product.where("timestamp").below(checkTime()).delete()
  .then(function (deleteCount) {
      console.log( "Deleted " + deleteCount + " objects");
  });
  </code></pre>