const countries = {
AF: 'Afghanistan',
AL: 'Albania',
HR: 'Croatia',
ID: 'Indonesia', // <<< make this one defaultSelected
ZW: 'Zimbabwe',
};
const EL_country = document.querySelector('#country');
const DF_options = document.createDocumentFragment();
Object.keys(countries).forEach(key => {
const isIndonesia = key === 'ID'; // Boolean
DF_options.appendChild(new Option(countries[key], key, isIndonesia, isIndonesia))
});
EL_country.appendChild(DF_options);
document.forms[0].reset(); // "Indonesia" is still selected