Well, I made another chat, like the socket.io one, except better! This one, instead of having those bogus alert prompts, we made a second page. We used localStorage too! Have fun people!
If you don't mind, this is still very vulnerable to XSS, and I'm still a beginner at it! I simply set my name to some HTML, then tried writing HTML in the messages. It seemed sometimes writing
<script>alert(1)</script> Would sometimes work, but
<img src=x onerror=alert(1)> always works. Overall though, this thing looks great, is very fast, and has a good way to use it. 10/10 Would make marquees again.