how can i figure out the last modified date of a html file im importing into my web app?
The html file is on another server and different users can make updates, when i retrieve the page i want to be able see when it was last updated so i can label the updated date on my homepage. I
Use the document.lastModified Javascript property.
quirksmode has a nice function to format the date too: http://www.quirksmode.org/js/lastmod.html
I assume you are using HTTP to retrieve the page.
In that case you can use the HEAD method of HTTP to get the header data of the file. (See http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html, 9.4)
Then you can check the "Last-Modified" header of the response. (See http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html, 14.29)
In case of some caching mechanism (proxy, browser caching) it might be necessary to include "Cache-Control: must-revalidate" in the request header. (See http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html, 14.9.4)
You could use the Last-Modfied Header from the response headers.
The Last-Modified entity-header field indicates the date and time at which the origin server believes the variant was last modified.
Last-Modified = "Last-Modified" ":" HTTP-date <script type="text/javascript"> <!-- document.write(document.lastModified); // --> </script> There are some proposed meta tag keys representing Dublin Core values that may be used. See: https://stackoverflow.com/a/14893974/895245