The File.lastModified
read-only property provides the last modified date of the file as the number of milliseconds since the Unix epoch (January 1, 1970 at midnight). Files without a known last modified date return the current date.
Syntax
var time = instanceOfFile.lastModified;
Value
A number that represents the number of milliseconds since the Unix epoch.
Example
Reading from file input
<input type="file" multiple id="fileInput">
const fileInput = document.getElementById('fileInput'); fileInput.addEventListener('change', function(event) { // files is a FileList object (simliar to NodeList) const files = event.target.files; for (let i = 0; i < files.length; i++) { const date = new Date(files[i].lastModified); alert(files[i].name + ' has a last modified date of ' + date); } });
Try the results out below:
Dynamically created files
If a File is created dynamically, the last modified time can be supplied in the new File()
constructor function. If it is missing, lastModified inherits the current time from Date.now()
at the moment the File object gets created.
var fileWithDate = new File([], 'file.bin', { lastModified: new Date(2017, 1, 1), }); console.log(fileWithDate.lastModified); //returns 1485903600000 var fileWithoutDate = new File([], 'file.bin'); console.log(fileWithoutDate.lastModified); //returns current time
Specifications
Specification | Status | Comment |
---|---|---|
File API The definition of 'lastModified' in that specification. |
Working Draft | Initial definition. |
Browser compatibility
Feature | Chrome | Edge | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
---|---|---|---|---|---|---|
File.lastModified | 13.0 | (Yes) | 15.0 (15.0) | 10.0 | 16.0 | No support |
Feature | Android | Edge | Firefox Mobile (Gecko) | IE Phone | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|
File.lastModified | No support | (Yes) | No support | No support | No support | No support |