JSFiddle - React, Tailwind, and code Playground

HTML

<ul id="lookup">
    <li id="li1">hidden</li>
    <li id="li2">shown</li>
    <li id="li3">hidden</li>
</ul>

CSS

#li1{
    display:none;
}
#li2{
    display:block;
}
#li3{
    display:none;
}

JavaScript

var lookup = document.getElementById('lookup');
for(i in lookup.children){
    var elementDisplay = window.getComputedStyle(lookup.children[i]).display;
    
    if(elementDisplay != 'none' ){
         alert(lookup.children[i].innerText);   
    }
}