Steps to reproduce
The HTML Standard’s event handler processing algorithm was recently updated to standardize on the most interoperable behavior between all browsers. Edge matches it in most respects, but does not seem to handle BeforeUnloadEvent correctly.
The relevant web platform tests are at http://w3c-test.org/html/browsers/browsing-the-web/unloading-documents/beforeunload-canceling.html. Edge fails some of them because of a strange cross-iframe restriction which is probably its own compatibility issue.
Spec discussion links:
Comments and activity
- Microsoft Edge Team
Changed Assigned To to “Steven K.”