FileException | Web API

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基本概念
Attribute
常量
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非标
此特征是非标准的，且不在标准轨道中。不要在面向 Web 的生产站点中使用它：它不适用于每个用户。实现之间可能存在大的不兼容性，且行为将来可能改变。

过时
This feature is obsolete. Although it may still work in some browsers, its use is discouraged since it could be removed at any time. Try to avoid using it.

在文件系统 API ， FileException object represents error conditions that you might encounter while accessing the file system using the synchronous API. It extends the FileException interface described in File Writer and adds several new error codes.

基本概念

Synchronous APIs do not have error callbacks, which makes it difficult to catch errors. The added complexity of using WebWorkers with this API makes debugging even more challenging. To simplify things a bit, wrap your worker code in a try/catch. When errors occur, forward them to the main app using postMessage() as in the following:

function onError(e) {
  postMEssage('ERROR:' + e.toString());
}
try {
  //Error is thrown if "log.txt" already exists.
var fileEntry = fs.root.getFile('log.txt', {create: true, exclusive:true}0;
} catch (e) {
  onErrror(e);
}

The sample code was borrowed from HTML5Rocks

属性

属性	类型	描述
`code`	`unsigned short`	The most appropriate error code for the condition.

常量

注意： Do not rely on the numeric values of the constants, which might change as the specifications continue to change. Use the constant names instead.

常量	值	描述
`ENCODING_ERR`	5	The URL is malformed. Make sure that the URL is complete and valid.
`INVALID_MODIFICATION_ERR`	9	The modification requested is not allowed. Examples of invalid modifications include moving a directory into its own child or moving a file into its parent directory without changing its name.
`INVALID_STATE_ERR`	7	The operation cannot be performed on the current state of the interface object. For example, the state that was cached in an interface object has changed since it was last read from disk.
`NO_MODIFICATION_ALLOWED_ERR`	6	The state of the underlying file system prevents any writing to a file or a directory.
`NOT_FOUND_ERR`	1	A required file or directory could not be found at the time an operation was processed. For example, a file did not exist but was being opened.
`NOT_READABLE_ERR`	4	The file or directory cannot be read, typically due to permission problems that occur after a reference to a file has been acquired (for example, the file or directory is concurrently locked by another application).
`PATH_EXISTS_ERR`	12	The file or directory with the same path already exists.
`QUOTA_EXCEEDED_ERR`	10	Either there's not enough remaining storage space or the storage quota was reached and the user declined to give more space to the database.
`SECURITY_ERR`	2	Access to the files were denied for one of the following reasons: The files might be unsafe for access within a Web application. Too many calls are being made on file resources. Other unspecified security error code or situations.
`TYPE_MISMATCH_ERR`	11	The user has attempted to look up a file or directory, but the Entry found is of the wrong type. For example, the app is accessing a DirectoryEntry when the user is requesting a FileEntry.

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
`FileException` 弃用非标	Chrome 13 — 29 Prefixed 不支持 13 — 29 Prefixed Prefixed Implemented with the vendor prefix: webkit	Edge No	Firefox No	IE No	Opera No	Safari No	WebView Android No	Chrome Android 18 — 29 Prefixed 不支持 18 — 29 Prefixed Prefixed Implemented with the vendor prefix: webkit	Firefox Android No	Opera Android No	Safari iOS No	Samsung Internet Android 1.0 — 3.0 Prefixed 不支持 1.0 — 3.0 Prefixed Prefixed Implemented with the vendor prefix: webkit

图例

不支持
非标。预期跨浏览器支持较差。
弃用。不要用于新网站。
要求使用供应商前缀或不同名称。

另请参阅

规范： File API: Directories and System Specification WD

参考：文件系统 API

介绍： Basic Concepts About the File System API

元数据

最后修改： 2019 年 3 月 23 日

在此页

基本概念

属性

常量

浏览器兼容性

图例

另请参阅

相关话题