https://github.com/webreflection/esimorp

An Inside Out Promise
https://github.com/webreflection/esimorp

cancelable cancellation promises rejectable resolvable

Last synced: about 1 month ago
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An Inside Out Promise

• Host: GitHub
• URL: https://github.com/webreflection/esimorp
• Owner: WebReflection
• License: isc
• Created: 2017-03-01T19:03:20.000Z (over 8 years ago)
• Default Branch: master
• Last Pushed: 2018-07-03T18:11:24.000Z (over 7 years ago)
• Last Synced: 2025-02-16T18:15:53.385Z (8 months ago)
• Topics: cancelable, cancellation, promises, rejectable, resolvable
• Language: HTML
• Size: 22.5 KB
• Stars: 7
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

          
# Esimorp [![Build Status](https://travis-ci.org/WebReflection/esimorp.svg?branch=master)](https://travis-ci.org/WebReflection/esimorp) [![Coverage Status](https://coveralls.io/repos/github/WebReflection/esimorp/badge.svg?branch=master)](https://coveralls.io/github/WebReflection/esimorp?branch=master)

Inside Out Promises.

The simplest, yet handy, resolvable and rejectable Promises for all developers use cases.

```js

// The constructor callback is optional.

// If provided, it's exactly the same

// that you would pass to a new Promise.

const promise = new Esimorp();

// you can already use the instance

// just like any other Promise

promise

  .then(console.log)

  .catch(console.error);

// ... and whenever it happens ...

promise.resolve('kudos');

```

### F.A.Q.

  * _can I `promise.then().resolve()` ?_ Nope, only the initial resolvable creator/owner can resolve it. No side effects at distance.

  * _can I safely pass around a `promise.then()` ?_ Absolutely, that just creates a new `Promise` copy that's not resolvable.

  * _how can I abort an operation ?_ It's up to you, but following there is an example.

```js

function fetchy(url) {

  const p = new Esimorp();

  const xhr = new XMLHttpRequest();

  // derive from Esimorp

  // to avoid external resolution

  const out = p.then();

  // expose only abort, delegating to xhr

  out.abort = xhr.abort.bind(xhr);

  // resolve indirectly out through Esimorp p

  xhr.addEventListener('abort', e => p.reject(e));

  xhr.addEventListener('error', e => p.reject(e));

  xhr.addEventListener('load', e => p.resolve(xhr));

  // perform the operation

  xhr.open('get', url);

  xhr.send();

  // return the Promise with abort delegate

  return out;

}

```

  * _what else could I do with this ?_ You could create Promises with a timeout and resolve or reject them before.

```js

const p = new Esimorp((res, rej) => {

  // reject in 5 seconds

  setTimeout(rej, 5000, 'timeout');

});

// but if resolved or rejected first is OK

setTimeout(() => p.resolve('OK'), 1000);

```

### License

(C) 2017 Andrea Giammarchi, [@WebReflection](https://twitter.com/WebReflection/), MIT Style License.