Question

Im a beginner and i see that line of code a lot on javascript files , for example :

window.onunload=function(){};

when should i use this and what is it role exactly ?

thank you .

Answer 1

onunload is an event that is triggered when the user navigates away from your page, or when the page is “unloaded”.

It’s triggered when a user follows a link, or closes the tab. It’s used for clean up. Like saving a user’s data when they leave the page. Usually it’s paired with onbeforeunload (which is called before onunload is using the same criteria) to warn a user that they have unsaved data.