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 read-only modificationTime property of the Metadata interface is a Date object which specifies the date and time the file system entry (or the data referenced by the entry) was last modified.A file system entry is considered to have been modified if the metadata or the contents of the referenced file (or directory, or whatever other kind of file system entry might exist on the platform in use) has changed.


var modificationTime = Metadata.modificationTime;


A Date timestamp indicating when the file system entry was last changed.


This example tries to get a particular working file at tmp/workfile.json. Once that file has been found, its metadata is obtained and the file's modification timestamp year is compared to the current year. If it was last modified in a year at least five prior to the current year, the file is removed and a new one is created.

workingDirectory.getFile("tmp/workfile.json", { create: true }, function(fileEntry) {
  fileEntry.getMetadata(function(metadata) {
    if ((new Date().getFullYear() - metadata.modificationTime.getFullYear()) >= 5) {
      fileEntry.remove(function() {
        workingDirectory.getFile("tmp/workfile.json", { create: true }, function(newEntry) {
          fileEntry = newEntry;
}, handleError); 

This API has no official W3C or WHATWG specification.

Browser compatibility

Update compatibility data on GitHub
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
Chrome Full support 13Edge ? Firefox No support NoIE No support NoOpera No support NoSafari No support NoWebView Android No support NoChrome Android Full support YesFirefox Android No support NoOpera Android No support NoSafari iOS No support NoSamsung Internet Android Full support Yes


Full support Ā 
Full support
No support Ā 
No support
Compatibility unknown Ā 
Compatibility unknown
Experimental. Expect behavior to change in the future.
Experimental. Expect behavior to change in the future.
Non-standard. Expect poor cross-browser support.
Non-standard. Expect poor cross-browser support.

See also