<!DOCTYPE html>
<html>
<body>
Select a fruit and click the button:
<select id="mySelect">
<option>Apple</option>
<option>Orange</option>
<option>Pineapple</option>
<option>Banana</option>
</select>
<button type="button" onclick="myFunction()">Display index</button>
<script>
function myFunction() {
var x = document.getElementById("mySelect").selectedIndex;
var y = document.getElementById("mySelect").options;
alert("Index: " + y[x].index + " is " + y[x].text);
}
</script>
</body>
</html>