Off the top of my head: - Overriding the fetch/XHR API for error monitoring (there's no other way to listen for them unless you use Service Workers) - Polyfil

Off the top of my head: - Overriding the fetch/XHR API for error monitoring (there's no other way to listen for them unless you use Service Workers) - Polyfilling features on top of existing APIs But you might not see them as "justified".