From 33058f2b292b3a581333bdfb21b8f671898c5060 Mon Sep 17 00:00:00 2001 From: Peter Bengtsson Date: Tue, 8 Dec 2020 14:40:17 -0500 Subject: initial commit --- files/zh-cn/web/api/idbfactory/open/index.html | 79 ++++++++++++++++++++++++++ 1 file changed, 79 insertions(+) create mode 100644 files/zh-cn/web/api/idbfactory/open/index.html (limited to 'files/zh-cn/web/api/idbfactory/open/index.html') diff --git a/files/zh-cn/web/api/idbfactory/open/index.html b/files/zh-cn/web/api/idbfactory/open/index.html new file mode 100644 index 0000000000..832a4ee7b2 --- /dev/null +++ b/files/zh-cn/web/api/idbfactory/open/index.html @@ -0,0 +1,79 @@ +--- +title: IDBFactory.open +slug: Web/API/IDBFactory/open +translation_of: Web/API/IDBFactory/open +--- +

{{APIRef("IDBFactory")}}

+
+

IDBFactory.open 方法用于打开一个数据库连接。本方法立即返回一个 {{domxref("IDBOpenDBRequest")}} 对象，但打开数据库的操作是异步执行的。

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+

连接数据库在一个单独的线程中进行，包括以下几个步骤：

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    +
  1. 指定数据库已经存在时： +
      +
    • 等待 {{domxref("versionchange")}} 操作完成。
      • +
    • 如果数据库已计划删除，那等着删除完成。
      • +
    +
    2. +
  2. 如果已有数据库版本高于给定的 version，中止操作并返回类型为 VersionError 的 DOMError 。
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  3. 如果已有数据库版本低于给定的 version，触发一个 versionchange 操作。
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  4. 如果数据库不存在，创建指定名称的数据库，将版本号设置为给定版本，如果给定版本号，则设置为1，and no object stores.
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  5. 创建数据库连接。
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+

如果操作成功执行，将触发 success 事件 on the request object that is returned from this method, with its result attribute set to the new {{domxref("IDBDatabase")}} object for the connection.

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If an error occurs while the database connection is being opened, then an error event is fired on the request object returned from this method.

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Syntax

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For the current standard:

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 IDBOpenDBRequest open (DOMString name, [EnforceRange] optional unsigned long long version);
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For the experimental version with options (see below):

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IDBOpenDBRequest open (DOMString name, optional IDBOpenDBOptions options);
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示例

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For the current standard:

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var request = window.indexedDB.open("toDoList", 4);
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For the experimental version with options (see below):

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var request = window.indexedDB.open("toDoList", {version: 4, storage: "temporary"});
+

参数

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+
+ name
+
+ 数据库名称
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+ 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
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+ options (version and storage) {{ NonStandardBadge() }}
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+ In Gecko, since version 26, you can include an options object as a parameter of {{ domxref("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 {{ bug("785884") }} for more details. This is a non-standard feature that we are looking to standardise sometime in the future.
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+
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Note: Data in temporary storage persists until the global limit for the pool is reached. The global limit calculation is relatively complex, but we are considering changing it (see  {{ Bug("968272") }}). When the global limit is reached, then data for the least recently used origin is deleted. There's also a group limit (eTLD+1 group/domain) which is currently 20% of the global limit. All requets that would exceed the group limit are just rejected.

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+

返回

+
+
+ {{domxref("IDBOpenDBRequest")}}
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+ The request object on which subsequent events related to this request are fired.
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+

Exceptions

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This method may raise a {{domxref("DOMException")}} with a DOMError of the following types:

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Exception描述
TypeErrorThe value of version is zero or a negative number or not a number.
+

Specifications

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{{page("/en-US/docs/Web/API/IDBFactory","Specifications")}}

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浏览器兼容性

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{{page("/en-US/docs/Web/API/IDBFactory","Browser_compatibility")}}

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