JSFiddle - React, Tailwind, and code Playground

HTML

<ul id="derp">
    <li>One</li>
    <li>One</li>
    <li>One</li>
    <li>One</li>
    <li>One</li>
    <li>One</li>
</ul>

JavaScript

jQuery(document).ready(function(){
    
    var count = jQuery("#derp li ").length;
    var interval = (10 / count) / 10;
    var newval = 1.0;
    
    jQuery("#derp li").each(function(i, item){
        if(i == 0) {
            newval = newval;
        } else {
            newval = parseFloat(newval) - parseFloat(interval);
        }
        jQuery(item).css('opacity', (newval));
    });
    
});