A rare use of AJAX remote scripting is to get information without actually retrieving a file. This is done through a HEAD request. This could be used to determine if a files exists, when a file was last modified, or the size of a file. However, by default, servers usually don't supply date modified or file size information for files that use server-side processing. There seems to be limited need to provide this information to a client for files from your server without downloading the file. But...
Click on any link in the following list and the header content will be retrieved.