javascriptでindexeddb内のキー値を削除について

●やりたいこと
１setValue関数で、
key値を"timestamp"＝new Date().getTime()）
とし、indexeddb内のobjectStore内に保存

２deleteValue

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8"/>
</head>
<body>
  <h3>登録・更新</h3>
  バリュー：<input type="number" id="newvalue" />
  <input type="button" value="設定" onclick="setValue()"/>
  <hr />
   
  <h3>参照</h3>
  <input type="button" value="全取得" onclick="getAll()"/>
  <hr />
   
  <h3>削除</h3>
  削除したい値のキー<input type="number" id="deletekey" />
  <input type="button" value="削除" onclick="deleteValue()"/>
  <hr />

  <h3>処理結果</h3>
  <div id="result"/>
</body>
<script>
  var db;
  var indexedDB = window.indexedDB || window.mozIndexedDB || window.msIndexedDB;
  if (indexedDB) {
    // データベースを削除したい場合はコメントを外します。
    //indexedDB.deleteDatabase("mydb");
    var openRequest = indexedDB.open("mydb", 1.0);
    openRequest.onupgradeneeded = function(event) {
      // データベースのバージョンに変更があった場合(初めての場合もここを通ります。)
      db = event.target.result;
      var store = db.createObjectStore("mystore", { keyPath: "timestamp"});
      store.createIndex("myvalueIndex", "myvalue");
 store.createIndex("myvalueIndex2","timestamp", "myvalue");
    }
     
    openRequest.onsuccess = function(event) {
          db = event.target.result;
        }
  } else {
    window.alert("このブラウザではIndexed DataBase API は使えません。");
  }
   
  function setValue(event) {
    var timestamp = new Date().getTime();
    var value = Number(document.getElementById("newvalue").value);
     
    var transaction = db.transaction(["mystore"], "readwrite");
    var store = transaction.objectStore("mystore");
     
    var request = store.put({ timestamp: timestamp, myvalue: value});
    request.onsuccess = function (event) {
      timestamp = new Date().getTime();
      document.getElementById("newvalue").value = "";
    }
  }
   

   
  function getAll(event) {
    var result = document.getElementById("result");
    result.innerHTML = "";
    var transaction = db.transaction(["mystore"], "readwrite");
    var store = transaction.objectStore("mystore");
    var request = store.openCursor();
    request.onsuccess = function (event) {
      if(event.target.result == null) {
        return;
      }
      var cursor = event.target.result;
          var data = cursor.value;
      result.innerHTML +=  "timestamp："  + data.timestamp +　"　key："  + cursor.primaryKey +  "  value：" + data.myvalue + "<br/>";
       
      cursor.continue();
    }
  }
   
  function deleteValue(event) {
    var Key = document.getElementById("deletekey").value;
    var result = document.getElementById("result");
    result.innerHTML = "";
   var transaction = db.transaction(["mystore"], "readwrite");
    var store = transaction.objectStore("mystore");
    var request = store.delete(Key);
    request.onsuccess = function (event) {
      result.innerHTML = "削除しました。";
    }
  }
 
</script>
</html>