JSFiddle - React, Tailwind, and code Playground

HTML

<span style="visibility:hidden;">H</span>	
<span>V</span>

<span style="visibility:hidden;">H</span>

<span>V</span>

CSS

body {
    font-family: monospace;
}

JavaScript

var elems = document.getElementsByTagName('span');

for (var i = 0; i < elems.length; i++) {
    if (elems[i].style.visibility === "hidden") {
        elems[i].style.visibility = "visible";
    } else {
        elems[i].style.visibility = "hidden";
    }
}