jQuery indexof
HTML
<select id="index">
<option>Japanese</option>
<option>English</option>
<option>Hindi</option>
<option>French</option>
<option>Telugu</option>
</select>
JavaScript
const languages = [ "English", "Hindi", "Japanese", "Marathi", "French" ];
$('#index').on('change', () => {
console.log(languages.indexOf($('#index').val(), 0))
});