File.lastModified is not supported by best browsers ? Alternatives?

Question

I have a file js that refresh every 5 minutes... In my code (always in javascript) i have a setInterval that should check if the file is refresh.

I would to do it with

File.lastModified  
//OR
File.lastModifiedDate  

But i read that isn't supported by all best browsers....is true?

https://developer.mozilla.org/en-US/docs/Web/API/File/lastModifiedDate#Browser_compatibility

Can you suggest me other alternatives ?

Thanks a lot and sorry fow my english....