// Function that returns a promise

var searchForNumber = function(number) {

    return new Promise(function(resolve, reject) {

      setTimeout(function() {

        var min = 1;

        var max = 10;

        var val = Math.floor(Math.random()*(max-min+1)+min);

        console.log('Value is: ' + val.toString());        

        return resolve(val);        

      }, 1000);

    });

};

​

// fn     : function that should return a promise.

// args   : the arguments that should be passed to fn.

// donefn : function that should check the result of the promise

//    and return true to indicate whether ploop should stop or not.

// promise: A promise value that is used internally by ploop and should never 

//    be passed in by the caller of ploop.

var ploop = function(fn, args, donefn, promise) {

    return (promise = promise || Promise.resolve(true))    

      .then(function() {

          return(fn.apply(null, args));

      })

      .then(function(result) {

        var finished = donefn(result);

        if(finished === true){

           return result;

        } else {

          return ploop(fn, args, donefn, promise);

        }

    });

};

​

var searchFor = 4;

​

var donefn = function(result) {

  return result == searchFor;

};

​

console.log('Searching for: ' + searchFor);

ploop(searchForNumber, [searchFor], donefn)

  .then(function(val) {

    console.log('Finally found! ' + val.toString());  

    process.exit(0);

  })

  .catch(function(err) {

    process.exit(1);

  });

​