How to fetch token in a function block

Question

i create a working heroku app from here

when i send to heroku app url/rtc/:channelName/:role/:tokentype/:uid/?expiry=

i get the token fine.

but how to do this in function block?

like the one from here

function fetchToken(uid, channelName, tokenRole) {

 return new Promise(function (resolve) {
     axios.post('http://<Your Host URL and port>/fetch_rtc_token', {
         uid: uid,
         channelName: channelName,
         role: tokenRole
     }, {
         headers: {
             'Content-Type': 'application/json; charset=UTF-8'
         }
     })
         .then(function (response) {
             const token = response.data.token;
             resolve(token);
         })
         .catch(function (error) {
             console.log(error);
         });
 })

}