How to overcome cache in a dumb browser?

Question

PHP

Hello. Need help.
JS library included.
$js_ml_file = 'templates/theme/js/com_abc/lib.js';
$js_ml = JURI::root().$js_ml_file.filemtime($js_ml_file);
$document -> addScript($js_ml);
That is, if the library changes, the unique
code after the library name will be changed in order to exclude the cache: lib.js?1234567890
Varnish cache cleared. The Joomla cache has been cleared.
All OK. But there is one person who has the old version of the library in the browser,
and the old bugs, respectively.
Options to clean his cache manually is not an option. The old school :) thinks that these are my problems.
He updated the browser, but no options.
Tell me where to dig? The browser is sort of like FireFox, maybe even an older version.
What else can be done? It's been 3 days now and his browser's cache hasn't cleared
automatically.

Answer 1

CTRL + F5 hold down for 10 seconds, maybe it will help :)