File: lastModifiedDate property

Note: This feature is available in Web Workers.

Deprecated: 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 compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.

Non-standard: This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.

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

Value

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

Examples

js
// fileInput is a HTMLInputElement: <input type="file" multiple id="my-file-input">
const fileInput = document.getElementById("my-file-input");

for (const file of fileInput.files) {
  console.log(
    `${file.name} has a last modified date of ${file.lastModifiedDate}`,
  );
}

Reduced time precision

To offer protection against timing attacks and fingerprinting, the precision of someFile.lastModifiedDate might get rounded depending on browser settings. In Firefox, the privacy.reduceTimerPrecision preference is enabled by default and defaults to 2ms. You can also enable privacy.resistFingerprinting, in which case the precision will be 100ms or the value of privacy.resistFingerprinting.reduceTimerPrecision.microseconds, whichever is larger.

For example, with reduced time precision, the result of someFile.lastModifiedDate.getTime() will always be a multiple of 2, or a multiple of 100 (or privacy.resistFingerprinting.reduceTimerPrecision.microseconds) with privacy.resistFingerprinting enabled.

js
// reduced time precision (2ms) in Firefox 60
someFile.lastModifiedDate.getTime();
// Might be:
// 1519211809934
// 1519211810362
// 1519211811670
// …

// reduced time precision with `privacy.resistFingerprinting` enabled
someFile.lastModifiedDate.getTime();
// Might be:
// 1519129853500
// 1519129858900
// 1519129864400
// …

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

BCD tables only load in the browser

See also