File: lastModifiedDate property

Note: This feature is available inWeb 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 thecompatibility 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 not standardized. We do not recommend using non-standard features in production, as they have limited browser support, and may change or be removed. However, they can be a suitable alternative in specific cases where no standard option exists.

ThelastModifiedDate read-only property of theFile interface returns the last modified date of the file. Files without a known last modified date return the current date.

Value

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

Examples

// fileInput is a HTMLInputElement: <input type="file" multiple>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 andfingerprinting, the precision ofsomeFile.lastModifiedDate might get rounded depending on browser settings. In Firefox, theprivacy.reduceTimerPrecision preference is enabled by default and defaults to 2ms. You can also enableprivacy.resistFingerprinting, in which case the precision will be 100ms or the value ofprivacy.resistFingerprinting.reduceTimerPrecision.microseconds, whichever is larger.

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

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