File.lastModifiedDate

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

Syntax

var time = instanceOfFile.lastModifiedDate

Value

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

Example

// 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.

Specifications

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 instead.

Browser compatibility

See also

• File