Calling callback function inside for loop doesn't work

Question

I am trying to run a callback function inside a for loop, but I am finding issues in executing the callback function. Seems like the function gets executed after the for loop is completed. For example if for loop has 2 iteration, then the function is executed only after the two for loop iteration is executed. Hence the execution of function is always done after the last iteration of for for loop. I am trying it really hard and have spend almost a day today looking at examples and have finally have used the closures as per the example provided in example in below link but still not getting the accurate result. https://www.geekabyte.io/2013/04/callback-functions-in-loops-in.html

Below is the code that I am using :

            let promoList = [];
            for(i = 0; i< availablePromoCount; i++){

              promoObj = {};
              promoObj.maxUsesUser = getAvailablePromoResults[i].MaxUsesUser //getAvailablePromoResults is a list coming from another function not shown here

              promoObj.promoCode = getAvailablePromoResults[i].PromoCode; // available promo code for this iteration

              promoList.push(promoObj);

              (function(clsn){
              
                  searchUserUsedPromo(userId, promoList[clsn].promoCode, (error, searchUserUsedPromoResults) => {
                    if (error) {
                      console.log(error);
                      return res.status(500).json({
                        success: 0,
                        message: "Some other error",
                        error: error,
                      });
                    }
                    console.log("Iteration of function is ", clsn);  // always iteration is last iteration and displays same and last iteration of i
                    
                    console.log("Searched promo code is ", promoList[clsn].promoCode);
                    timesUsed = searchUserUsedPromoResults.length;
                    console.log("Times Used", timesUsed);
                    console.log("Max uses user", promoList[i].maxUsesUser);

                  });
              
              })(i)

              count++;
              if(getAvailablePromoResults.length == count){
              
                return res.status(200).json({
                  success: 1,
                  availablePromoList: availablePromoList,
                });

              }
            } 

searchUserUsedPromo() calls order.model.js to get the db query and executes

searchUserUsedPromo: (userId, promoCode, callback) => {
    pool.query(
      `select * from userpromo where UserId = ? and PromoCode = ? and Used = 1`,
      [
       userId, 
       promoCode
      ],
      (error, results, fields) => {
        console.log(results);
        if (error) {
          return callback(error);
        }
        return callback(null, results);
      }
    );
  },