CssSelectors

function search() {
   const listTown= document.getElementById('towns');

   const resultElement=document.getElementById('result');
   const searchtext= document.querySelector('#searchText').value;

   let matchcount=0;
   const townElements=Array.from(listTown.children);
   for (const town  of townElements) {
      if (town.innerHTML.includes(searchtext)) {
         town.style.textDecoration='underline';
         town.style.fontWeight='bold';
         matchcount++;
      }
   }

   const res=`${matchcount} matches found`;
   resultElement.textContent=res;
}