JSFiddle - React, Tailwind, and code Playground

JavaScript

h=new Array(50).join(" ")+("HelloWorld".split("").join("   "));
i=80;

function f(){
        if(i--){
            if(i>50){
                h=h.substr(1);
            }else{
                h=h.replace(" ",(i==16)?" ":"");
            }
            document.body.innerHTML="<pre>"+h.substr(0,50)+"</pre>";
            setTimeout(f,99);
        }
}
f();