JSFiddle - React, Tailwind, and code Playground
by pradeep
HTML
<select>
<option>India (+91)</option>
<option>Afganisthan (+145)</option>
</select>
JavaScript
$('select').each(function(){
var selectedCountry = $(this).children("option").val();
var result = selectedCountry.match(/\((.*)\)/);
alert(result[1]);//this will show the value of the atribute of that option.
$(this).children("option").attr("data-value",result[1]);
});