IDBOpenDBRequest.onupgradeneeded

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onupgradeneeded 特性为 IDBOpenDBRequest interface is the event handler for the upgradeneeded event, triggered when a database of a bigger version number than the existing stored database is loaded.

The event passed to the listener is an IDBVersionChangeEvent .

Inside the event handler function you can include code to upgrade the database structure, as shown in the example below.

注意： 此特征可用于 Web 工作者 .

句法

IDBOpenDBRequest.onupgradeneeded = function(event) { ... };

范例

In the following example you can see the onupgradeneeded handler being used to update the database structure if a database with a higher version number is loaded. For a full working example, see our 待办通知 app ( 实时查看范例 )。

var db;
// Request version 3 of the database.
var request = window.indexedDB.open("library", 3);
// This event handles the event whereby a new version of the
// database needs to be created. Either one has not been created
// before, or a new version number has been submitted via the
// window.indexedDB.open line above.
request.onupgradeneeded = function(event) {
  db = request.result;
  db.onerror = function(errorEvent) {
    note.innerHTML += '<li>Error loading database.</li>';
  };
  if (event.oldVersion < 1) {
    // Version 1 is the first version of the database.
    var store = db.createObjectStore("books", {keyPath: "isbn"});
    var titleIndex = store.createIndex("by_title", "title", {unique: true});
    var authorIndex = store.createIndex("by_author", "author");
  }
  if (event.oldVersion < 2) {
    // Version 2 introduces a new index of books by year.
    var bookStore = request.transaction.objectStore("books");
    var yearIndex = bookStore.createIndex("by_year", "year");
  }
  if (event.oldVersion < 3) {
    // Version 3 introduces a new object store for magazines with two indexes.
    var magazines = db.createObjectStore("magazines");
    var publisherIndex = magazines.createIndex("by_publisher", "publisher");
    var frequencyIndex = magazines.createIndex("by_frequency", "frequency");
  }
};
request.onerror = function(event) {
  note.innerHTML += '<li>Error loading database.</li>';
};
request.onsuccess = function(event) {
  note.innerHTML += '<li>Database initialised.</li>';
  db = request.result;
  populateAndDisplayData();
};

规范

规范	状态	注释
索引数据库 API 2.0 The definition of 'onupgradeneeded' in that specification.	推荐
索引数据库 API 草案 The definition of 'onupgradeneeded' 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
`onupgradeneeded`	Chrome 24 24 不支持 23 — 57 Prefixed Prefixed Implemented with the vendor prefix: webkit	Edge 12	Firefox 16 16 不支持 10 — 16 Prefixed Prefixed Implemented with the vendor prefix: moz	IE 部分支持 10	Opera 15	Safari 7	WebView Android Yes Yes 不支持 ? — 57 Prefixed Prefixed Implemented with the vendor prefix: webkit	Chrome Android 25 25 不支持 25 — 57 Prefixed Prefixed Implemented with the vendor prefix: webkit	Firefox Android 22	Opera Android 14	Safari iOS 8	Samsung Internet Android 1.5 1.5 不支持 1.5 — 7.0 Prefixed Prefixed Implemented with the vendor prefix: webkit

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 )。
upgradeneeded event

元数据

最后修改： 2020 年 1 月 22 日

IndexedDB API
IDBOpenDBRequest
特性
1. onblocked
2. onupgradeneeded
事件
1. blocked
2. upgradeneeded
继承：
1. IDBRequest
2. EventTarget
IndexedDB 相关页面

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句法

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