我是一个使用inxeddb的新手，正在尝试从一个存储中获取数据。存储中包含数据，但是由于某种原因，代码在尝试设置var tx后停止。如果我遗漏了什么，请告诉我。下面是我尝试获取这本书的函数：

function getBook(){
    var tx = db.transaction("book", "readonly");
    var store = tx.objectStore("book");
    var index = store.index("by_getid");

    var request = index.get("<?php echo $_GET['book'] ?>");
    request.onsuccess = function() {
      var matching = request.result;
      if (matching !== undefined) {
         document.getElementById("text-container").innerHTML = matching.text;
      } else {
        alert('no match');
        report(null);
      }
    };
}

已解决版本：

function getBook(){
  var db;
  var request = indexedDB.open("library", 1);  

  request.onsuccess = function (evt) {
    db = request.result; 
    var transaction = db.transaction(["book"]);
    var objectStore = transaction.objectStore("book");
    var requesttrans = objectStore.get(<?php echo $_GET['book'] ?>);

    requesttrans.onerror = function(event) {

    };

    requesttrans.onsuccess = function(event) {
      alert(requesttrans.result.text);
    };      
  };
}