在此页

• 句法
• 范例
• Reduced time precision
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

弃用
This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the 兼容性表格 at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.

File.lastModifiedDate read-only property returns the last modified date of the file. Files without a known last modified date returns the current date.

句法

var time = instanceOfFile.lastModifiedDate
					

值

A 日期 object indicating the date and time at which the file was last modified.

范例

// fileInput is a HTMLInputElement: <input type="file" multiple id="myfileinput">
var fileInput = document.getElementById("myfileinput");
// files is a FileList object (simliar to NodeList)
var files = fileInput.files;
for (var i = 0; i < files.length; i++) {
  alert(files[i].name + " has a last modified date of " + files[i].lastModifiedDate);
}
					

Reduced time precision

To offer protection against timing attacks and fingerprinting, the precision of someFile.lastModifiedDate.getTime() might get rounded depending on browser settings.

In Firefox, the privacy.reduceTimerPrecision preference is enabled by default and defaults to 20us in Firefox 59; in 60 it will be 2ms.

// reduced time precision (2ms) in Firefox 60
someFile.lastModifiedDate.getTime();
// 1519211809934
// 1519211810362
// 1519211811670
// ...
// reduced time precision with `privacy.resistFingerprinting` enabled
someFile.lastModifiedDate.getTime();
// 1519129853500
// 1519129858900
// 1519129864400
// ...
					

In Firefox, you can also enable privacy.resistFingerprinting , the precision will be 100ms or the value of privacy.resistFingerprinting.reduceTimerPrecision.microseconds , whichever is larger.

规范

Though present in early draft of the File API spec, this property has been removed from it and is now non-standard. Use File.lastModified 代替。

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
lastModifiedDate 弃用 非标	Chrome 13	Edge 12	Firefox 不支持 15 — 61	IE 10	Opera 16	Safari 不支持 No	WebView Android Yes	Chrome Android Yes	Firefox Android 不支持 No	Opera Android 不支持 No	Safari iOS 不支持 No	Samsung Internet Android Yes

图例

完整支持

完整支持

不支持

不支持

非标。预期跨浏览器支持较差。

弃用。不要用于新网站。

弃用。不要用于新网站。

另请参阅

• File

元数据

• 最后修改： 2019 年 3 月 23 日

相关话题

1. File
2. 构造函数

   1. File()
3. 特性

   1. fileName
   2. fileSize
   3. lastModified
   4. lastModifiedDate
   5. mozFullPath
   6. 名称
   7. type
   8. webkitRelativePath
4. 方法

   1. getAsBinary()
   2. getAsDataURL()
   3. getAsText()
5. 继承：

   1. Blob
6. 文件 API 相关页面

   1. Blob
   2. FileList
   3. FileReader
   4. FileReaderSync