Promise "loop" using the Bluebird library

promise_while_loop.js

var Promise = require('bluebird');

var promiseWhile = function(condition, action) {
    var resolver = Promise.defer();

    var loop = function() {
        if (!condition()) return resolver.resolve();
        return Promise.cast(action())
            .then(loop)
            .catch(resolver.reject);
    };

    process.nextTick(loop);

    return resolver.promise;
};


// And below is a sample usage of this promiseWhile function
var sum = 0,
    stop = 10;

promiseWhile(function() {
    // Condition for stopping
    return sum < stop;
}, function() {
    // The function to run, should return a promise
    return new Promise(function(resolve, reject) {
        // Arbitrary 250ms async method to simulate async process
        setTimeout(function() {
            sum++;
            // Print out the sum thus far to show progress
            console.log(sum);
            resolve();
        }, 250);
    });
}).then(function() {
    // Notice we can chain it because it's a Promise, this will run after completion of the promiseWhile Promise!
    console.log("Done");
});

Doing async function on each members of the array

global.Promise.asyncOnEach = Promise.method(function(arr,action,steps) {
    if(!steps) steps = 0;
    console.log("Currently working on index:",steps,"Value:",arr[steps]);
    if(arr.length<=steps) {
        console.log("Finished working on the array, now will return it");
        console.log(arr);
        return arr;
    }
    return new Promise((resolve,reject)=>{
        action(arr[steps]).then((v)=>{
            arr[steps] = v;
            console.log(v);
            resolve(arr);
        }).catch((e)=>{
            reject(e);
        });
    }).then(Promise.asyncOnEach.bind(null,arr,action,steps+1));
});

Usage:

Promise.asyncOnEach([3,6,9],asyncFunc)
.then((arr)=>{
    console.log("The result is:",arr);
    res.send("OK");
}).catch((e)=>{
    console.log(e);
    res.send("error");
});