After your script ends, how would you send more information to the browser?

Here is my simplified understanding of your question: Browser requests page from Server. Server runs script, script returns partial output, Server sends output to browser, script ends...Server sends what to the browser?</>

Here is my simplified understanding of what I think you want: Browser requests page from Server. Server runs script, script returns partial output, Server sends output to browser, script loops and sends more info to the server, server continues sending output to the browser until the script ends.</>