working search bar html

<script>
function myFunction() {
  // Declare variables

    var input, filter, 
ul, li, a, i, txtValue;
  input = document.getElementById('myInput');
  
filter = input.value.toUpperCase();
  ul = 
document.getElementById("myUL");
  li = 
ul.getElementsByTagName('li');

  // Loop through all 
list items, and hide those who don't match the search query
  for (i = 0; i < 
li.length; i++) {
    a = li[i].getElementsByTagName("a")[0];

      
  txtValue = a.textContent || a.innerText;
    
if (txtValue.toUpperCase().indexOf(filter) > -1) {
      
li[i].style.display = "";
    } 
else {
      
li[i].style.display = "none";
    
}
  }
}

</script>