promitto
v0.1.2promitto
promitto is a tiny Promise/Deferred library for JavaScript environments which helps you when dealing with async tasks in a pretty and clean way. It provides an elegant, standard and simple API
It's compatible with the Promise/A+ spec and provides useful features for asynchronous promise-based programming patterns
promitto is written in Wisp, a Clojure-like language which transpiles into plain JavaScript. It exploits functional programming common patterns such as lambda lifting, pure functions, higher-order functions, function composition and more
Installation
Node.js
npm install promitto --save
Browser
Via Bower package manager
bower install promitto --save
Or loading the script remotely (just for testing or development)
<script src="//rawgithub.com/h2non/promitto/master/promitto.js"></script>
Environments
It works properly in any ES5 compliant engine
- Node.js
- Chrome >= 5
- Firefox >= 3
- Safari >= 5
- Opera >= 12
- IE >= 9
Basic usage
var promitto = require('promitto')
Using Deferred pattern
var p = require('promitto')
function doAsyncJob() {
var defer = p.defer()
get('http://www.google.com', function (err, res) {
if (err) defer.reject(err)
else defer.resolve(res)
})
return defer.promise
}
doAsyncJob().then(function (data) {
console.log(data)
}).catch(function (reason) {
console.error('Error:', reason)
})
Using Promise pattern (Promise/A+ / ES6 compatible)
var Promise = require('promitto').Promise
var promise = Promise(function doJob(resolve, reject, notify) {
get('http://www.google.com', function (err, res) {
if (err) reject(err)
else resolve(res)
})
})
promise.then(function (data) {
console.log(data)
}).catch(function (reason) {
console.error('Error:', reason)
})
API
promitto(callback)
Create a new promitto promise passing a function task
promitto(function readPackage(resolve, reject, notify) {
fs.readFile('./package.json', function (err, data) {
if (err) reject(err)
else resolve(JSON.parse(data))
})
}).then(function (pkg) {
console.log('Name:', pkg.name)
}).catch(function (reason) {
console.error('Error:', reason)
})
promitto.defer()
Creates a Deferred object
promitto.Promise(task)
Creates a new Promise compatible with the ES6 promise interface
promitto.when(value)
Wrap an object that might be a value or a 3rd party promise
This is useful when you are dealing with an object that might or might not be a promise, or if the promise comes from a source that can't be trusted
promitto.reject(reason)
Creates a promise that is resolved as rejected with the specified reason
promitto.resolve(reason)
Creates a promise that is resolved with the specified reason
promitto.all([promises])
Combines multiple promises into a single promise that is resolved when all of the input promises are resolved
Returns a single promise that will be resolved with an array/hash of values, each value corresponding to the promise at the same index/key in the promises array/hash
promitto.isPromise(value)
Return if a given value is a compatible promise
Deferred
resolve(value)
Resolves the derived promise with the value
reject(reason)
Rejects the derived promise with the reason
.
This is equivalent to resolving it with a rejection constructed via promitto.reject
notify(reason)
Provides updates on the status of the promise's execution. This may be called multiple times before the promise is either resolved or rejected
promise
Expose the Promise object associated with this deferred
Promise
then(onResolve, onReject, onNotify)
Regardless of when the promise was or will be resolved or rejected, then calls one of the success or error callbacks asynchronously as soon as the result is available.
The callbacks are called with a single argument: the result or rejection reason. Additionally, the notify callback may be called zero or more times to provide a progress indication, before the promise is resolved or rejected
catch(callback)
Catch promise resolve as reject status.
Shorthand for promise.then(null, onReject)
finally(callback)
Allows you to observe either the fulfillment or rejection of a promise, but to do so without modifying the final value. This is useful to release resources or do some clean-up that needs to be done whether the promise was rejected or resolved
notify(callback)
Handle the promise progress while it's still on pending state. This is useful when you want to report the state of the process until it's finally fulfilled (resolved or rejected)
Contributing
Wanna help? Cool! It will be appreciated :)
You must add new test cases for any new feature or refactor you do, always following the same design/code patterns that already exist
Tests specs are completely written in Wisp language. Take a look to the language documentation if you are new with it. You should follow the Wisp language coding conventions
Development
Only node.js is required for development
Clone/fork this repository
$ git clone https://github.com/h2non/promitto.git && cd promitto
Install package dependencies
$ npm install
Compile code
$ make compile
Run tests
$ make test
Browser sources bundle generation
$ make browser
Release a new version
$ make release
License
MIT - Tomas Aparicio