JSFiddle - React, Tailwind, and code Playground

HTML

<h1 id="hi">Hi!</h1>

JavaScript

//create a collection
    var myFont = [ "times", "helvetica", "verdana", "georgia"];
    //record the last index used
    var lastIndex;
    setInterval(function(){ 
        //pick a random number within the collection's range
        // make sure it's not the same as the last one used
        do{
            index = Math.floor(Math.random() * myFont.length);
        } while(lastIndex === index);
        // record the font used
        lastIndex = index;
        //set the font
        document.getElementById('hi').style.fontFamily = myFont[index];
        
    }, 500);