JSFiddle - React, Tailwind, and code Playground

by InferOn

HTML

<ul>
    <li id="item_1">Item 1</li>
    <li id="item_2">Item 2</li>
    <li id="item_4">Item 4</li>
</ul>
<div id='test'></div>

JavaScript

var p = $(".list");
var result = 1;
var pp = $("li[id^='item_']", p);
for (var i = 0; i < pp.length; i++) {

    if (result == parseInt(pp[i].id.split('item_')[1])) {
        result++;
        continue;
    } else {
        $('#test')[0].innerText = result;
    }
}