Phone number prefix jquery -

i want prefix phone number + sign when user starts entering phone number in form.how using jquery without using mask plugin.i have tried using mask plugin need jquery library reference.

this pretty simple solution force leading + sign

working demo

$(function () {     $("input").on("input propertychange", function () {     if ($(this).val().indexof("+") === -1) {         $(this).val("+" + $(this).val());     }   }); });