Retry and async function (a function that returns a Promise)

retryAsyncFunction.js

//wrap setTimeout with an async-await friendly function
function sleep(ms){
    console.log("sleep starts");
    let resolveFn;
    let pr = new Promise(res => resolveFn = res);
    setTimeout(() => {
        console.log("sleep ends");
        resolveFn();
    }, ms);
    return pr;
}

//fn: function returning a Promise
//if the Promise is rejected we'll retry up to "attempts" times, with a "timeout" in between
//returns a new function with retry logic
function addRetryToAsyncFn(fn, attempts, timeout){
    return async (...args) => {
        while (attempts--){
            try{
                return await fn(...args);
            }
            catch(ex){
                console.log("attempt failed");
                if (!attempts)
                    throw ex;
            }
            await sleep(timeout);
        }
   
    };
}

//test code:
class TicketsProvider{
    constructor(){
        this.requestsCounter = 1;
    }

    //we give a ticket out of 3 requests
    getTicketAsync(){
        return new Promise((res, rej) => {
            setTimeout(()=> {
                if (this.requestsCounter++ % 3 === 0)
                    res({ticketId: (this.requestsCounter - 1) / 3});
                else
                    res(null);
            }, 1000);
        });
    }

}

var ticketsProvider = new TicketsProvider();

async function getAndFormatNextTicket(user){
    //console.log("inside getAndFormatNextTicket");
    let ticket = await ticketsProvider.getTicketAsync();
    if (ticket === null)
        throw new Error("no ticket available");
    else
        return `[${ticket.ticketId} - ${user}]`;
}

//async main
(async () => {
    try{
        let formattedTicket = await addRetryToAsyncFn(getAndFormatNextTicket, 5, 1000)("Francois");
        console.log(`formattedTicket: ${formattedTicket}`);
    
        formattedTicket = await addRetryToAsyncFn(getAndFormatNextTicket, 2, 1000)("Francois");
        console.log(`formattedTicket: ${formattedTicket}`);
    }
    catch(ex){
        console.log("Exception: " + ex.message);
    }
})();