Skip to content

Instantly share code, notes, and snippets.

@jaskiratr
Forked from victorquinn/promise_while_loop.js
Created January 3, 2017 22:48
Show Gist options
  • Save jaskiratr/baa9a9c47f7e6dfc5d26ef45f752575a to your computer and use it in GitHub Desktop.
Save jaskiratr/baa9a9c47f7e6dfc5d26ef45f752575a to your computer and use it in GitHub Desktop.
Promise "loop" using the Bluebird library
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");
});
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment