promiseback

#promiseback ^{[![Version Badge][npm-version-svg]][npm-url]}

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Accept an optional node-style callback, and also return a spec-compliant Promise!

API

``js
var promiseback = require('promiseback');
var callback = function (err, value) {};

/ without a promise: /
promiseback(callback);
/*
- will throw if callback is not a function
- returns a "deferred"
- has resolve/reject methods, and promise property
- will call callback as expected when deferred is resolved
*/

/ with a promise: /
promiseback(promise, callback);
/*
- will throw if callback is truthy and not a function
- promise will be converted to a Promise, so you can pass a value as well
- returns a Promise
- will call callback as expected when the promise is fulfilled
*/
`

Examples

Using deferreds:
`js
var promiseback = require('promiseback');

module.exports = function doSomethingCool(thing, callback) {
// If callback is not provided, this code will simply return a normal promise.
// If callback is provided but is not a function, promiseback will immediately throw a TypeError.

// "deferred" is an object with reject/resolve methods, and a promise property.
var deferred = promiseback(callback);
if (thing) {
deferred.resolve(thing);
} else {
deferred.reject(thing);
}
return deferred.promise;
};
`

Using a straight promise, when you can get it from somewhere else:
`js
var promiseback = require('promiseback');

module.exports = function doSomethingCool(thing, callback) {
// If callback is not provided, this code will simply return a normal promise.
// If callback is provided but is not a function, promiseback will immediately throw a TypeError.

var newThingPromise = makeNewThing(thing);
return promiseback(newThingPromise, callback);
};
`

Tests


Simply clone the repo, npm install, and run npm test`

[npm-url]: https://npmjs.org/package/promiseback
[npm-version-svg]: http://versionbadg.es/ljharb/promiseback.svg
[travis-svg]: https://travis-ci.org/ljharb/promiseback.svg
[travis-url]: https://travis-ci.org/ljharb/promiseback
[deps-svg]: https://david-dm.org/ljharb/promiseback.svg
[deps-url]: https://david-dm.org/ljharb/promiseback
[dev-deps-svg]: https://david-dm.org/ljharb/promiseback/dev-status.svg
[dev-deps-url]: https://david-dm.org/ljharb/promiseback#info=devDependencies
[testling-png]: https://ci.testling.com/ljharb/promiseback.png
[testling-url]: https://ci.testling.com/ljharb/promiseback
[npm-badge-png]: https://nodei.co/npm/promiseback.png?downloads=true&stars=true