var request = indexedDB.open('dzxcx',3);
        request.onerror = function(event) {
            alert('失败' + event.target.errorCode);
        }
        var users = [
             {
                username : "zhangsan",
                password : "zhangsan",
                email : "zhangsan@126.com"
            },
            {
                username : "lisi",
                password : "lisi",
                email : "lisi@126.com"
            }
        ]
        request.onupgradeneeded = function(event) {
            var db = event.target.result;
            var ObjectStore = db.createObjectStore("users",{keyPath:"username"});
            ObjectStore.createIndex("username","username",{unique : false});
            ObjectStore.createIndex("password","password",{unique : false});
            ObjectStore.createIndex("email","email",{unique : true});

            for(var i in users) {
                ObjectStore.add(users[i])
            }
        }

        function addContent() {
            request.onerror = function(e) {
                alert("错误");
            }
            request.onupgradeneeded = function(e) {
                var db = event.target.result;
                var transaction = db.transaction(["users"],"readwrite");
                transaction.oncomplete = function(event) {
                  alert("All done!");
                };
                var objectStore = transaction.objectStore("users");
                for (var i in users) {
                  var request = objectStore.add(users[i]);
                  request.onsuccess = function(event) {
                    // event.target.result == customerData[i].ssn
                    alert("成功")
                  };
                }
            }
        }
        addContent();

而且这个 transaction.objectStore 这个objectStore是从哪里来的 是什么意思啊？ 简单点来说
我就是想了解 怎么插入数据 删除数据 获取数据 求帮助啊！