Iterate function and stop depending on callback value

Question

How do I iterate over a asynchronous function in nodejs stopping depending on callback return?

Example:

suppose I have following function

var fn1 = function(i, callback){
    // code here
    callfunction(i, function(err, p2){
         if(err) throw err;
         if(something) return callback(true);
         else return callback(false);
    });
}

I need to iterate and call for i=1,2,3,... until my callback returns false.

I tried using async whilst, but I do not think it can helps me, because the test function also needs callback, and the function for test and iteratee are same, I cannot call twice.

I am not able to understand your requirements! can you make it more clear.? — Yash Ganatra, Jul 24 '17 at 16:29

score 0 · Answer 1 · answered Jul 24 '17 at 16:54

If I understand your problem correctly. What about some recursion

const maxTries = 10;

// just a stupid counter to run a be able to change return value
let numberOfCalls = 0;

const asyncCall = () => {
  if (numberOfCalls === 9) {
    return Promise.resolve(false);
  }
  numberOfCalls += 1;
  return Promise.resolve();
};

function iterate(calls = 0) {
  if (maxTries === calls) {
    return Promise.resolve();
  }
  return asyncCall().then(value => {
    if (value === false) {
      return value;
    }
    return iterate(calls + 1);
  });
}

iterate().then(result => {
  if (result === undefined) {
    //to many tries
  }
  console.log('result', result);
});

Iterate function and stop depending on callback value

1 Answers1