Whoever did this is, unsurprisingly, not very good at it. They did a simple javascript window.location, but in such a weird way. It's half way through the site's HTML, which I suspect is why your browser gets about halfway through loading the main page before redirecting. It's also duplicated 4 times, and it's partway through a link declaration. I mean, it works, obviously, but it makes no sense to me why anyone would do it like that.
givesendgone.wtf isn't even behind CloudFlare or anything like that. It takes two seconds to see they're using Namecheap's basic web hosting. I get not dedicating your own infrastructure to a hijack like this, but why the hell wouldn't you even try to hide your host? They're probably dumb enough to have used their legitimate payment information for the domain and hosting.