For those wondering what such a thing could be useful besides showing some rad golfing skills, be informed that this is pretty nice and really fast prototyping

For those wondering what such a thing could be useful besides showing some rad golfing skills, be informed that this is pretty nice and really fast prototyping tool. I made similar for myself [1] and I can honestly say I use it daily: you can take the dataURI, bookmark it, make a keword (i.e. the `%s` sumbsitiution) for it and from this point you have instant, offline "Codepen" in your URL bar. Let's say you want to check if your browser still supports the marquee tag: just type `s <marquee>...` into url, hit enter and see. Most online sandboxes with live preview would not even load in such timespan. [1] this is for usage as keyword URL; it "saves" its state into location hash so you can return to it or share or whatever; such "save" currently fails in Chrome when loaded from pure datauri because security. also you can test different mimetypes (like application/xhtml+xml or image/svg+xml) in it, what comes in handy from time to time. Golfed just slightly. data:text/html;charset=utf-8,<!DOCTYPE%20html><title>HTML%20sandbox%201.0.8</title><style>*{box-sizing:border-box;width:100vw;height:100vh;margin:0}[id]{border:inset;width:50vw;float:left}</style><body%20onload=A.value=decodeURIComponent((L=location).hash.slice(1)||'');T=W=0;E=RegExp('^'+(D='data:text/html;charset=utf-8,'));F=function(){if(W!=(V=A.value))W=V,M=V.match(/(^data:.+?,)?([^]*)/),I.src=(M[1]||D)+encodeURIComponent(M[2])};F()%3E%3Ctextarea%20autofocus%20id=A%20onkeyup=clearTimeout(T);T=setTimeout(F,400)%20onblur=L.hash=I.src.replace(E,%27%27)%3E%3C/textarea%3E%3Ciframe%20id=I%3E#%s