how to achive resend OTP using firebase auth

how can Resend OTP after 60 sec. using firebase library, currently using this
https://github.com/firebase/quickstart-js/blob/master/auth/phone-invisible.html

1) called this on first Send OTP window.recaptchaVerifier = new firebase.auth.RecaptchaVerifier('sign-in-button', {

});

woring fine its sending Firts OTP. but i have added timer if 60 sec. cross. it will Resend OTP button

not its not send Next OTP so how can I achvie That?

2) On Resend OTP click calling Same window.recaptchaVerifier = new firebase.auth.RecaptchaVerifier('sign-in-button', {

});