Stop session countdown on browser close codeigniter

bagaimana bikin stop timer countdown ketika close browser lalu on browser dan login kembali waktu tetap, tidak berubah seperti ketika close browser. Dari panduan https://stackoverflow.com/questions/26965232/codeigniter-session-destroy-on-browser-close-doesnt-work. Bagaimana masukin kode berikut. " var sessionExpire = function(e){ //here ajax request to expire session }; window.unload = sessionExpire;

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