JSFiddle - React, Tailwind, and code Playground

HTML

<select id="mySelectBox" onfocus="populate(this);">
</select>

JavaScript

function populate(a) {
  buildingOptions = jQuery.parseJSON("{\"buildings\":[{\"code\":\"a\",\"name\":\"theName\"},{\"code\":\"b\",\"name\":\"fgd\"}]}");
  for (var i = 0; i < buildingOptions.buildings.length; i++) {
    $('#mySelectBox').append('<option value=\"' + buildingOptions.buildings[i].code + '\">' + buildingOptions.buildings[i].name + '</option>');
  }

}