A
@preactjs app fitting in a tweet:
data:text/html,<html><body><script src="
unpkg.com/preact"></script><script>let c=0,b=document.body,{h,render}=preact,r=()=>{render(h("div",null,c," ",h("button",{onClick(){c++,r()}},"+1")),b,b.firstChild)};r();</script></body></html>