If you’re looking for a way to keep a PHP script running on the server even after the user navigates from the page or hits the stop button, you can use the “ignore_user_abort” flag in the php.ini file or set it using ini_set function.

How does PHP know that a user has aborted a page load then?

Paul explains how this works in PHP at his blog stating that PHP has no way of knowing that a user has actually aborted a page load until it sends out some output to the brower.

“You’ve probably heard of the setting in php.ini ignore_user_abort, and how it allows you to ignore a user aborting page load and thus terminating your script mid way through. Today I found out that didn’t quite mean what I thought that meant.”

Head over to Paul’s article: When does a user abort? - <?paul