Some websites (such as Poal.co and MediaWiki sites) [ask the user for confirmation](https://code-maven.com/prevent-leaving-the-page-using-plain-javascript) users from leaving the page. I have observed that if I click *close* on a browser window, one tab with an unsaved edit rescues the entire window from closure. Spared me quite a few headaches. Also, there are add-ons for deactivating keyboard shortcuts such as `Ctrl+Q` for closing the entire browser.