How to use handlebars for autocomplete search bar with javascript?

Currently I am working to make a autocomplete search bar for ghost cms and I have to use handlebars for it. I have done it using html which is wrong so what can I do to implement handlebars template. this is the html part

<div class="autocomplete" style="width:300px;">
   <input id="myInput" type="text" name="myCountry" placeholder="Search">
</div>

Javascript part is:-

<script>
function autocomplete(inp, arr) {
  var currentFocus;
  inp.addEventListener("input", function(e) {
      var a, b, i, val = this.value;
      closeAllLists();
      if (!val) { return false;}
      currentFocus = -1;
      a = document.createElement("DIV");
      a.setAttribute("id", this.id + "autocomplete-list");
      a.setAttribute("class", "autocomplete-items");
      this.parentNode.appendChild(a);
      for (i = 0; i < arr.length; i++) {
        if (arr[i].substr(0, val.length).toUpperCase() == val.toUpperCase()) {
          b = document.createElement("DIV");
          b.innerHTML = "<strong>" + arr[i].substr(0, val.length) + "</strong>";
          b.innerHTML += arr[i].substr(val.length);
          b.innerHTML += "<input type='hidden' value='" + arr[i] + "'>";
          b.addEventListener("click", function(e) {
              inp.value = this.getElementsByTagName("input")[0].value;
              closeAllLists();
          });
          a.appendChild(b);
        }
      }
  });
  inp.addEventListener("keydown", function(e) {
      var x = document.getElementById(this.id + "autocomplete-list");
      if (x) x = x.getElementsByTagName("div");
      if (e.keyCode == 40) {
        currentFocus++;
        addActive(x);
      } else if (e.keyCode == 38) { 
        currentFocus--;
        addActive(x);
      } else if (e.keyCode == 13) {
        e.preventDefault();
        if (currentFocus > -1) {
          if (x) x[currentFocus].click();
        }
      }
  });
  function addActive(x) {
    if (!x) return false;
    removeActive(x);
    if (currentFocus >= x.length) currentFocus = 0;
    if (currentFocus < 0) currentFocus = (x.length - 1);
    x[currentFocus].classList.add("autocomplete-active");
  }
  function removeActive(x) {
    for (var i = 0; i < x.length; i++) {
      x[i].classList.remove("autocomplete-active");
    }
  }
  function closeAllLists(elmnt) {
    var x = document.getElementsByClassName("autocomplete-items");
    for (var i = 0; i < x.length; i++) {
      if (elmnt != x[i] && elmnt != inp) {
        x[i].parentNode.removeChild(x[i]);
      }
    }
  }
 document.addEventListener("click", function (e) {
      closeAllLists(e.target);
  });
}

var countries = ["Afghanistan","Albania","Algeria","Andorra","Angola","Anguilla","Antigua","Argentina","Armenia","Aruba","Australia","Austria","Azerbaijan","Bahamas","Bahrain","Bangladesh","Barbados","Belarus","Belgium","Belize","Benin","Bermuda","Bhutan","];

autocomplete(document.getElementById("myInput"), countries);
</script>

So, what my problem is I am doing this in a .hbs file I don't know how to use handlebars for the search functionality. If I try to create a

It doesn't work how should I link my handlebars part with my javascript part. I have people doing it with jquery but it just went over my head. So can anyone help please. PS:- If you are unable to understand I share more details also.