IDBDatabase.transaction()

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transaction 方法在 IDBDatabase interface imm ediately returns a transaction object ( IDBTransaction ) containing the IDBTransaction.objectStore method, which you can use to access your object store.

注意： 此特征可用于 Web 工作者 .

句法

IDBDatabase.transaction(storeNames);
IDBDatabase.transaction(storeNames, mode);

参数

"durability" -- the durability constrints for the transction.
Valid values are: "default" , "strict" ，和 "relaxed" .

storeNames

The names of object stores that are in the scope of the new transaction, declared as an array of strings. Specify only the object stores that you need to access.
If you need to access only one object store, you can specify its name as a string. Therefore the following lines are equivalent:

var transaction = db.transaction(['my-store-name']);
var transaction = db.transaction('my-store-name');

If you need to access all object stores in the database, you can use the property


									IDBDatabase.objectStoreNames

var transaction = db.transaction(db.objectStoreNames);

Passing an empty array will throw an exception.

mode 可选

The types of access that can be performed in the transaction. Transactions are opened in one of three modes:


								readonly


								readwrite

and


								readwriteflush

(non-standard, Firefox-only.)


								versionchange

mode can't be specified here. If you don't provide the parameter, the default access mode is


								readonly

. To avoid slowing things down, don't open a


								readwrite

transaction unless you actually need to write into the database.

If you need to open the object store in


								readwrite

mode to change data, you would use the following:

var transaction = db.transaction('my-store-name', "readwrite");

As of Firefox 40, IndexedDB transactions have relaxed durability guarantees to increase performance (see bug 1112702 ), which is the same behaviour as other IndexedDB-supporting browsers. Previously in a readwrite transaction IDBTransaction.oncomplete was fired only when all data was guaranteed to have been flushed to disk. In Firefox 40+ the complete event is fired after the OS has been told to write the data but potentially before that data has actually been flushed to disk. The complete event may thus be delivered quicker than before, however, there exists a small chance that the entire transaction will be lost if the OS crashes or there is a loss of system power before the data is flushed to disk. Since such catastrophic events are rare most consumers should not need to concern themselves further.

注意 : In Firefox, if you wish to ensure durability for some reason (e.g. you're storing critical data that cannot be recomputed later) you can force a transaction to flush to disk before delivering the complete event by creating a transaction using the experimental (non-standard) readwriteflush mode (see IDBDatabase.transaction .) This is currently experimental, and can only be used if the dom.indexedDB.experimental pref is set to true in about:config .

details 可选

Dictionary of other settings, supported only by Chrome:

返回值

IDBTransaction 对象。

异常

此方法可能引发 DOMException of one of the following types:

异常	描述
`I nvalidStateError`	`close()` method has previously been called on this `IDBDatabase` 实例。
`NotFoundError`	An object store specified in in the `storeNames` parameter has been deleted or removed.
`TypeError`	The value for the `mode` parameter is invalid.
`InvalidAccessError`	The function was called with an empty list of store names.

范例

In this example we open a database connection, then use transaction() to open a transaction on the database. For a complete example, see our 待办通知 app ( 实时查看范例 )。

var db;
// Let us open our database
var DBOpenRequest = window.indexedDB.open("toDoList", 4);
DBOpenRequest.onsuccess = function(event) {
  note.innerHTML += '<li>Database initialised.</li>';
  // store the result of opening the database in the db variable.
  // This is used a lot below
  db = DBOpenRequest.result;
  // Run the displayData() function to populate the task list with
  // all the to-do list data already in the IDB
  displayData();
};
// open a read/write db transaction, ready for adding the data
var transaction = db.transaction(["toDoList"], "readwrite");
// report on the success of opening the transaction
transaction.oncomplete = function(event) {
  note.innerHTML += '<li>Transaction completed: database modification finished.</li>';
};
transaction.onerror = function(event) {
  note.innerHTML += '<li>Transaction not opened due to error. Duplicate items not allowed.</li>';
};
// you would then go on to do something to this database
// via an object store
var objectStore = transaction.objectStore("toDoList");
// etc.

规范

规范	状态	注释
索引数据库 API 2.0 The definition of 'transaction()' in that specification.	推荐
索引数据库 API 草案 The definition of 'transaction()' in that specification.	推荐

浏览器兼容性

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request. 更新 GitHub 上的兼容性数据

	桌面						移动
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`transaction`	Chrome 24 24 23 — 24 Prefixed Prefixed Implemented with the vendor prefix: webkit	Edge 12	Firefox 16 16 10 — 16 Prefixed Prefixed Implemented with the vendor prefix: moz	IE 部分支持 10	Opera 15	Safari 7	WebView Android Yes	Chrome Android 25	Firefox Android 22	Opera Android 14	Safari iOS 8	Samsung Internet Android 1.5

图例

完整支持
部分支持
要求使用供应商前缀或不同名称。

另请参阅

使用 IndexedDB
开始事务： IDBDatabase
使用事务： IDBTransaction
设置一系列键： IDBKeyRange
检索并使您的数据改变： IDBObjectStore
使用光标： IDBCursor
参考范例：待办通知 ( 实时查看范例 )。

元数据

最后修改： Jun 30, 2020

IndexedDB API
IDBDatabase
特性
方法
1. close()
2. createObjectStore()
3. deleteObjectStore()
4. transaction()
事件
1. versionchange
继承：
1. EventTarget
IndexedDB 相关页面

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句法

参数

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异常

范例

规范

浏览器兼容性

图例

另请参阅

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