How to prevent IE11 pop up (Are you sure you want to leave this page)

问题

I am working on a page that I have nothing to type but a dropdown to select, but in IE11 when I try to move on to the next page, it will pop up the message. I would like to prevent this pop up from happening. So I just wonder what is the default behavior of that pop up in IE11(As it does not appear in either Chrome or Firefox) and how to prevent the pop up

回答1:

A more important question to ask is: "Why IE11 is popping up that alert?".

Are you leaving a secure page for an insecure one? I.e. make sure to call the secure booking API, or let the browser choose, by not explicitly specifying the protocol:

var url = '//api.booking_site.url/api_endpoint';

This will call either the secure or insecure version of the url depending if you're currently browsing a secure or insecure site.

If you just want to get rid of the pop-up, assuming the pop-up you mention is an alert box, you can overwrite alert:

window.alert = function() { return true; }

回答2:

This looks like it's a result of the return value from onbeforeunload. Apparently, instead of returning null you should return nothing.

See also onBeforeUnload handler says null in IE

来源：https://stackoverflow.com/questions/22535881/how-to-prevent-ie11-pop-up-are-you-sure-you-want-to-leave-this-page