Динамическое добавление optgroup по символам

function group(select) { 
  const oldGroups = select.querySelectorAll('optgroup'); 
   
  for (const group of oldGroups) { 
    const options = group.querySelectorAll('option'); 
    select.appendChild(select); 
    select.removeChild(group); 
  } 
   
  const options = select.querySelectorAll('option'); 
   
  const groups = {}; 
  for (const option of options) { 
    const firstLetter = option.innerText[0]; 
    if (firstLetter) { 
      if (!groups.hasOwnProperty(firstLetter)) { 
        groups[firstLetter] = []; 
      } 
      groups[firstLetter].push(option); 
    } 
  } 
   
  for (const letter of Object.keys(groups)) { 
    const group = document.createElement('optgroup'); 
    group.label = letter; 
    select.appendChild(group); 
 
    for (const option of groups[letter]) { 
      group.appendChild(option); 
    } 
  } 
} 
 
const $select = document.querySelector('#select'); 
group($select);

<select id="select"> 
        <option value="1">Andromed</option> 
        <option value="2">AnkosiManila</option> 
        <option value="3">Backend</option> 
        <option value="4">Bravisiimo</option> 
        <option value="5">Cokolada</option> 
        <option value="6">Cerny</option> 
        <option value="7">Mapping</option> 
        <option value="8">Marroni</option> 
        <option value="9">NugetPack</option> 
        <option value="10">Jaguar</option> 
</select>