TL;DR<p>extract some value from the file that changes with its content --like content's md5, or modified timestamp-- and append it to the file name<p>for example, let's say "index.js" and its md5 is "30c2234"
(shortened for readability)<p><pre><code> <script src="file-30c2234.js">
</code></pre>
later when you modify the file, the hash change, and clients start to request the new one.<p>this allows to set cache's evict time in doomsday