Untitled

<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<style>
* {
  box-sizing: border-box;
}
body {
  font: 16px Arial;
}
.autocomplete {
  /*the container must be positioned relative:*/
  position: relative;
  display: inline-block;
}
input {
  border: 1px solid transparent;
  background-color: #f1f1f1;
  padding: 10px;
  font-size: 16px;
}
input[type=text] {
  background-color: #f1f1f1;
  width: 100%;
}

.autocomplete-items {
  position: absolute;
  border: 1px solid #d4d4d4;
  border-bottom: none;
  border-top: none;
  z-index: 99;
  /*position the autocomplete items to be the same width as the container:*/
  top: 100%;
  left: 0;
  right: 0;
}
.autocomplete-items div {
  padding: 10px;
  cursor: pointer;
  background-color: #fff;
  border-bottom: 1px solid #d4d4d4;
}
.autocomplete-items div:hover {
  /*when hovering an item:*/
  background-color: #e9e9e9;
}
.autocomplete-active {
  /*when navigating through the items using the arrow keys:*/
  background-color: DodgerBlue !important;
  color: #ffffff;
}
</style>
</head>

<body>

<h2>Autocomplete</h2>

<p>Start typing:</p>

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

<script>
function autocomplete(inp, arr, car) {
  var currentFocus;

  inp.addEventListener("input", function(e) {
      var a, b, i, val = this.value;
      closeAllLists();
      if (!val) { return false;}

	  var search = val.indexOf(car);
	  var longi = val.length;

	  if (longi <= 1) { return false;}
	  if (search == -1) { return false;}

	  var splited = val.split(car);
	  var sizeAfterAt = splited[1].length + 1;
	  var valueInput = splited[0];

      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, sizeAfterAt).toUpperCase() == val.substr(search, val.length).toUpperCase()) {
          b = document.createElement("DIV");
          b.innerHTML = "<strong>" + valueInput + arr[i].substr(0, sizeAfterAt) + "</strong>";
          b.innerHTML += arr[i].substr(sizeAfterAt);
          b.innerHTML += "<input type='hidden' value='" + valueInput + 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 = ["@gmail.com", "@hotmail.com", "@outlook.com", "@yahoo.com"];

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

</body>
</html>