JSFiddle - React, Tailwind, and code Playground

HTML

<div id="main"></div>

CSS

#main {
    border: 1px solid #ccc;
}
.element {
    border: 1px dashed #444;
    height: 20px;
}

JavaScript

for (i = 0; i < 5; i++) { 
    var maxId = 0;
	$("#main .element *[id]").each(function() {
		if(maxId < $(this).attr("id")){ maxId = $(this).attr("id")}
	});
	maxId = maxId + 1;
	$('#main').append('<div class="element" id="'+maxId+'">');
}