JSFiddle - React, Tailwind, and code Playground

HTML

<div id="controlAddIn"></div>

JavaScript

init();
CreateOption("Select1", "fuu");
CreateOption("Select1", "fuu2");
CreateOption("Select2", "fuu");
CreateOption("Select2", "fuu");


function init() {

				createElement('h2', 'Määrät ja varastopaikat', 
							  {id: 'heading', style: 'color:skyblue;font-family:arial;text-align:left;'}, 
							  null, 'controlAddIn');
							  
				createElement('input', null,
							  {id: 'qtybox', type: 'number', step: '0.01', class: 'inputbox', style: 'width:15%;display:inline-block;white-space:nowrap;'},
							  null, 'controlAddIn');
				createElement('select', null,
							  {id: 'Select1', name: 'drop1', class: 'dropdwn', style: 'width:15%;', onchange: 'SelectedOne()'},
							  null,'controlAddIn');
			  createElement('select', null,
							  {id: 'Select2', name: 'drop2', class: 'dropdwn', style: 'width:30%;'},
							  null,'controlAddIn');
							  //[options[0], options[1], options[2], options[3]], 
							  
				createElement('button', null,
							  {id: 'Button1', name: 'button1',
							  class: 'dropbtn', style: 'width:20%;', onclick: 'ButtonPress()'},
							  [document.createTextNode("Lisää")], 'controlAddIn');
				
			RaiseAddInReady();
        }

		function createElement(){
			var element  = document.createElement(arguments[0]),
				text     = arguments[1],
				attr     = arguments[2],
				append   = arguments[3],
				appendTo = arguments[4];

			for(var key = 0; key < Object.keys(attr).length ; key++){
				var name = Object.keys(attr)[key],
					 value = attr[name],
					 tempAttr = document.createAttribute(name);
					 tempAttr.value = value;
				element.setAttributeNode(tempAttr)
			}
			
			if(append){
				for(var _key = 0; _key < append.length; _key++) {
					element.appendChild(append[_key]);
				}
			}

			if(text) element.appendChild(document.createTextNode(text));

			if(appendTo){
				var target = appendTo === 'body' ? document.body : document.getElementById(appendTo);
				target.appendChild(element)
			}       

			return...