IDBFactory.open

name

数据库名称

version

指定数据库版本，当你想要更改数据库格式（比如增加对象存储，非增加记录），必须指定更高版本，通过 versionchange 来更改

options (version and storage) 非标准

In Gecko, since version 26, you can include an options object as a parameter of IDBFactory.open that contains the version number of the database, plus a storage value that specifies whether you want to use permanent (the default value) storage for the IndexedDB, or temporary storage (aka shared pool.) See Firefox bug 785884 for more details. This is a non-standard feature that we are looking to standardise sometime in the future.

IDBOpenDBRequest

The request object on which subsequent events related to this request are fired.

This method may raise a DOMException with a DOMError of the following types:

使用当前规范的 version 参数调用 open 的示例：

const request = window.indexedDB.open("toDoList", 4);

带有 options 的实验性版本（见下文）：

const note = document.querySelector("ul");

// 打开数据库的第四个版本
const DBOpenRequest = window.indexedDB.open("toDoList", 4);

// 这两个事件处理器处理数据库成功打开或失败的情况
DBOpenRequest.onerror = (event) => {
  note.appendChild(document.createElement("li")).textContent =
    "Error loading database.";
};

DBOpenRequest.onsuccess = (event) => {
  note.appendChild(document.createElement("li")).textContent =
    "Database 已初始化。";

  // 将打开数据库的结果存储到 db 变量中。
  // 这在后面的打开事务等操作中经常使用。
  db = DBOpenRequest.result;
};