cheatsheets/promise.md

title	category
Promises	JavaScript

Based on the Promise API reference (mozilla.org). {:.brief-intro.center}

Creating promises

new Promise(function (ok, err) {
  doStuff(function () {
    if (success) { ok(); }
    else { err(); }
  });
})

Consuming promises

promise
  .then(okFn, errFn)
  .catch(errFn)

Multiple promises

var promises = [
  promise1(), promise2(), ...
]

// succeeds when all succeed
Promise.all(promises)
  .then(function (results) {
  });

// succeeds when one finishes first
Promise.race(promises)
  .then(function (result) {
  });

Converting other promises

return Promise.resolve("result");
return Promise.resolve(promise);
return Promise.resolve(thenable);

return Promise.reject("reason");

Promise.resolve($.get('http://google.com'))
.then(...)