# thenify

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[![Downloads][downloads-image]][downloads-url]

Promisify a callback-based function using [`any-promise`](https://github.com/kevinbeaty/any-promise).

- Preserves function names
- Uses a native promise implementation if available and tries to fall back to a promise implementation such as `bluebird`
- Converts multiple arguments from the callback into an `Array`
- Resulting function never deoptimizes
- Supports both callback and promise style

An added benefit is that `throw`n errors in that async function will be caught by the promise!

## API

- Turn async functions into promises

```js
var thenify = require('thenify');

var somethingAsync = thenify(function somethingAsync(a, b, c, callback) {
  callback(null, a, b, c);
});
```

- Backward compatible with callback

```js
var thenify = require('thenify').withCallback;

var somethingAsync = thenify(function somethingAsync(a, b, c, callback) {
  callback(null, a, b, c);
});

// somethingAsync(a, b, c).then(onFulfilled).catch(onRejected);
// somethingAsync(a, b, c, function () {});
```

### var fn = thenify(fn)

Promisifies a function.

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[gitter-url]: https://gitter.im/thenables/thenify
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[github-url]: https://github.com/thenables/thenify/tags
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[travis-url]: https://travis-ci.org/thenables/thenify
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[coveralls-url]: https://coveralls.io/r/thenables/thenify
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[david-url]: https://david-dm.org/thenables/thenify
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[license-url]: LICENSE
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[downloads-url]: https://npmjs.org/package/thenify