JSFiddle - React, Tailwind, and code Playground
by psoares
HTML
<form action="/Config.aspx/SDKHome/SaveSections" id="SaveSections" method="post">
<input name="[0].SchemaName" type="hidden" value="contactSection" />
<ul creator="attrCreator" data-dojo-type="dojo.dnd.Source" class="section container dojoDndSource"
style="list-style-type: none;">
<li class="dojoDndItem">
<input name="[0].DefinedAttributes[0].SchemaName" type="text" value="firstname" />
</li>
<li class="dojoDndItem">
<input name="[0].DefinedAttributes[1].SchemaName" type="text" value="jobtitle" />
</li>
</ul>
</form>
JavaScript
dojo.require("dojo.dnd.Source");
dojo.ready(function(){
var ul = dojo.query("ul.section").pop();
var lastLiInput = dojo.query("ul li:last-child>input").pop();
var lastLiInputName = dojo.attr(lastLiInput, "name");
var X = 1 + parseInt(lastLiInputName.replace(/.*DefinedAttributes\[(\d+)\].*/, '$1'));
var newLi = dojo.create("li", { class : "dojoDndItem" }, ul);
dojo.create("input", {
name : "[0].DefinedAttributes[" + X + "].SchemaName",
type : "text",
value : "otherValue"
}, newLi);
});