JSFiddle - React, Tailwind, and code Playground
HTML
<select id="sel"><option id="opt">Choose one</option></select>
JavaScript
var arr=[{key:'aaa',value:'hello'},{key:'bbb',value:'Hi'},{key:'ccc',value:'Ohhhh'}];
var html = '';
for(var i = 0;i < arr.length ; i++){
console.log(arr[i]['key'])
html += '<option value="' + arr[i]['key'] + '">' + arr[i]['value'] + '</option>';
}
$("#sel").append(html);