JSFiddle - React, Tailwind, and code Playground

HTML

<select id="vehicletype">
    <option>type1</option>
</select>

JavaScript

var ajaxURL = "/echo/json/";
var fireAjax = new Request.JSON({
    url: ajaxURL,
    method:'POST',
    data: {
        json: JSON.encode({
            opt1: 'option 1',
            opt2: 'option 2'
        })
    },
    onSuccess:function(resultjson){
                if(resultjson.length!=0){
                    var elSelect = new Element('option',{'html':'First component', 'value':'All' }).injectInside($('vehicletype'));
                   Object.each(resultjson,function(value,key){
                       new Element('option',{'value':key,'html':value}).inject($('vehicletype'));
                       //sschecker[0].registerAnotherElement($('vehicletype'));
                   });
                    
                }
            }
}).send();