JSFiddle - React, Tailwind, and code Playground

by SpAm

HTML

<select id="mySelect">
  
</select>

JavaScript

for (var m=0; m<3; m++) {
                var gr = document.createElement("optgroup");
                gr.label = "Optgroup "+m;
 
                for (var n=0; n<4; n++) {
                    var op = document.createElement("option");
                    op.innerHTML = "BLAH "+n;
                    op.value = n;
                    gr.appendChild(op);
                }
                mySelect.appendChild(gr);
            }