javascript - How to monitor browser refresh, close, and back behavior on PC?

Question

How to monitor browser refresh, close, and back behavior on PC? Then pop up the custom layer? I have tried onbeforeunload method. No alert pops up.

仅有的幸福 · Answer

unload cannot preventDefault, the reason is obvious when you think about it, to prevent users from being unable to close the webpage

This is what you should do:

onbeforeunload = function (){
  if (unsaved) return '本次编辑未保存, 确认关闭网页?'
}