for loop exit before callback is finished

Question

I have a for loop which is calling an async function. I need this function to then call a callback at the end of the for loop but only when all my async functions have returned their result. I have tried this:

for(var i = 0; i < vaccinsCount; i++){
    getVaccinAddress(i, address, provider, function(result){
       if(result.success){
         console.log("result:" + result.values);
         vaccines.push(result.values);
       } else {
         callback({success: false, message: result.message}); 
       }
   });
}
callback({success: true, values: vaccines}); 

instead what is happening is that the code enters the for loop then call then async function then exits straigh away. How could i get around this ?

getVaccinAddress is the Async Function that does a server call.

EDIT

I am using NodeJS, therefore the solution is to then use bluebird, I however have no idea on how to implement this with bluebird.

Answer 1

You can call callback() when vaccines.length is equal to vaccinsCount

for(var i = 0; i < vaccinsCount; i++) {
  (function(i) {
    getVaccinAddress(i, address, provider, function(result) {
       if(result.success) {
         console.log("result:" + result.values);
         vaccines.push(result.values);
         if (vaccines.length === vaccinsCount) {
            // call `callback()` here
         }            
       }
    });
  })(i);
}