JSFiddle - React, Tailwind, and code Playground

JavaScript

require([
    'dojo/dom-construct',
    'dojo/query',
    'dojo/NodeList-dom', // provides query(...).orphan()
    'dojo/domReady!'
], function(dom_construct, query) {

    // get your html snippet; hardcoded here for convenience and example
    var html_snippet = [
        '<div data-dojo-type="dijit/form/DropDownButton" id="dropDownBtn">  <span>Register</span>  <div data-dojo-type="dijit/TooltipDialog" id="dlg1">     <label for="name">Name:</label> <input data-dojo-type="dijit/form/TextBox" id="name" name="name"><br>     <label for="hobby">Hobby:</label> <input data-dojo-type="dijit/form/TextBox" id="hobby" name="hobby"><br>     <button data-dojo-type="dijit/form/Button" type="submit">Save</button>  </div></div>'
    ].join(''),
        has_customerid = false;
    
    var node = dom_construct.toDom(html_snippet);

    if (!has_customerid) {
        console.log(query('#dropDownBtn', node));
    }
    
    document.body.appendChild(node);
});