Vow

Promises/A+ implementation. See https://github.com/promises-aplus/promises-spec.

Getting Started

###In the Node.js### You can install using Node Package Manager (npm):

npm install vow

###In the Browsers###

<script type="text/javascript" src="vow.min.js"></script>

Also RequireJS module format supported.

API

• Creating promise
• Promise API
  • fulfill
  • reject
  • isFulfilled
  • isRejected
  • isResolved
  • valueOf
  • then
  • fail
  • always
  • spread
  • done
  • timeout
  • sync
• Vow API
  • isPromise
  • when
  • fail
  • always
  • spread
  • done
  • isFulfilled
  • isRejected
  • isResolved
  • fulfill
  • reject
  • resolve
  • all
  • allResolved
  • any
  • timeout

####Vow.promise([value])#### Create a new promise if no value given, or create a new fulfilled promise if the value is not a promise, or returns value if the given value is a promise.

var promise = Vow.promise(), // create a new promise
    fulfilledPromise = Vow.promise('ok'), // create a new fulfilled promise
    anotherPromise = Vow.promise(existingPromise); // anotherPromise is equal an existingPromise

###Promise API### ####fulfill(value)#### Fulfill promise with given value

var promise = Vow.promise();
promise.fulfill('completed'); // fulfill promise with 'completed' value

####reject(reason)#### Reject promise with given reason

var promise = Vow.promise();
promise.reject(Error('internal error')); // reject promise with Error object

####isFulfilled()#### Returns whether the promise is fulfilled

var promise = Vow.promise();
promise.isFulfilled(); // returns false
promise.fulfill('completed');
promise.isFulfilled(); // returns true

####isRejected()#### Returns whether the promise is rejected

var promise = Vow.promise();
promise.isRejected(); // returns false
promise.reject(Error('internal error'));
promise.isRejected(); // returns true

####isResolved()#### Returns whether the promise is fulfilled or rejected

var promise = Vow.promise();
promise.isResolved(); // returns false
promise.fulfill('completed'); // or promise.reject(Error('internal error'));
promise.isResolved(); // returns true

####valueOf()#### Returns value of the promise:

• value of fulfillment, if promise is fullfilled
• reason of rejection, if promise is rejected
• undefined, if promise is not resolved

####then([onFulfilled], [onRejected])#### Arranges for:

• onFulfilled to be called with the value after promise is fulfilled,
• onRejected to be called with the rejection reason after promise is rejected.

Returns a new promise. See Promises/A+ specification for details.

var promise = Vow.promise();
promise.then(
    function() { }, // to be called after promise is fulfilled
    function() { }); // to be called after promise is rejected

####fail(onRejected)#### Arranges to call onRejected on the promise's rejection reason if it is rejected. Shortcut for then(null, onRejected).

var promise = Vow.promise();
promise.fail(
    function() { // to be called after promise is rejected
    });
promise.reject(Error('error'));

####always(onResolved)#### Arranges to call onResolved on either the promise's value if it is fulfilled, or on it's rejection reason if it is rejected. Shortcut for then(onResolved, onResolved).

var promise = Vow.promise();
promise.always(
    function() { // to be called after promise is fulfilled or rejected
    });
promise.fulfill('ok'); // or promise.reject(Error('error'));

####spread([onFulfilled], [onRejected])#### Like "then", but "spreads" the array into a variadic value handler. It useful with Vow.all, Vow.allResolved methods.

var promise1 = Vow.promise(),
    promise2 = Vow.promise();

Vow.all([promise1, promise2]).spread(function(arg1, arg2) {
    // arg1 should be "1", arg2 should be "'two'"
});
    
promise1.fulfill(1);
promise2.fulfill('two');

####done()#### Terminate a chain of promises. If the promise is rejected, throws it as an exception in a future turn of the event loop.

var promise = Vow.promise();
promise.reject(Error('Internal error'));
promise.done(); // exception to be throwed

####timeout(timeout)#### Returns a new promise that to be rejected after a timeout if promise does not resolved beforehand.

var promise = Vow.promise(),
    promiseWithTimeout1 = promise.timeout(50),
    promiseWithTimeout2 = promise.timeout(200);

setTimeout(
    function() {
        promise.fulfill('ok');
    },
    100);

promiseWithTimeout1.fail(function(e) {
    // promiseWithTimeout to be rejected after 50ms
});

promiseWithTimeout2.then(function(val) {
    // promiseWithTimeout to be fulfilled with "'ok'" value
});

####sync(withPromise)#### Synchronize promise state with withPromise state. Shortcut for:

withPromise.then(
    function(val) {
        promise.fulfill(val);
    },
    function(err) {
        promise.reject(err);
    });

###Vow API###

####isPromise(value)#### Returns whether the given value is a promise.

Vow.isPromise('value'); // returns false
Vow.isPromise(Vow.promise()); // returns true

####when(value, [onFulfilled], [onRejected])#### Static equivalent for promise.then. If given value is not a promise, value is equivalent to fulfilled promise.

####fail(value, onRejected)#### Static equivalent for promise.fail. If given value is not a promise, value is equivalent to fulfilled promise.

####always(value, onResolved)#### Static equivalent for promise.always. If given value is not a promise, value is equivalent to fulfilled promise.

####spread(value, [onFulfilled], [onRejected])#### Static equivalent for promise.spread. If given value is not a promise, value is equivalent to fulfilled promise.

####done(value)#### Static equivalent for promise.done. If given value is not a promise, value is equivalent to fulfilled promise.

####isFulfilled(value)#### Static equivalent for promise.isFulfilled. If given value is not a promise, value is equivalent to fulfilled promise.

####isRejected(value)#### Static equivalent for promise.isRejected. If given value is not a promise, value is equivalent to fulfilled promise.

####isResolved(value)#### Static equivalent for promise.isResolved. If given value is not a promise, value is equivalent to fulfilled promise.

####fulfill(value)#### Returns a promise that has already been fulfilled with the given value. If value is a promise, returned promise will be fulfilled with fulfill/rejection value of given promise.

####reject(reason)#### Returns a promise that has already been rejected with the given reason. If reason is a promise, returned promise will be rejected with fulfill/rejection value of given promise.

####resolve(value)#### Returns a promise that has already been fulfilled with the given value. If value is a promise, returns promise.

####all(promisesOrValues)#### Returns a promise to be fulfilled only after all items in promisesOrValues is fulfilled, or to be rejected when the first promise is rejected.

####allResolved(promisesOrValues)#### Returns a promise to be fulfilled only after all items in promisesOrValues is resolved.

var promise1 = Vow.promise(),
    promise2 = Vow.promise();
    
Vow.allResolved([promise1, promise2])
    .spread(function(promise1, promise2) {
        promise1.valueOf(); // returns 'error'
        promise2.valueOf(); // returns 'ok'
    });

promise1.reject('error');
promise2.fulfill('ok');

####any(promisesOrValues)#### Returns a promise to be fulfilled only any item in promisesOrValues is fulfilled, or to be rejected when all items is rejected (with reason of first rejected item).

####timeout(promise, timeout)#### Static equivalent for promise.timeout. If given value is not a promise, value is equivalent to fulfilled promise.