leahciMic/promise-preserve

# promise-preserve

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Preserve the result in a promise chain.

## Install

```sh
npm install --save `promise-preserve`
```

## Usage

```js
var preserve = require('promise-preserve');

var promise = new Promise(function(resolve, reject) {
  resolve('Hello world!');
});

promise.then(preserve(function(result) {
  console.log(result); // prints 'Hello world!';
  return 'foobar';
}).then(function(result) {
  // prints 'Hello world!'; as promise-preserve preserved the value of the
  // promise chain
  console.log(result);
  return 'foobar';
}).then(function(result) {
  // prints 'foobar' as the previous function did not preserve the result
  console.log(result);
});
```

## API

### `preserve(fn)` preserve a function

Wraps the function so that when it is called, it does not modify the result in
a promise chain.

### `preserve(obj, name)` preserve a method

Wraps the method so that when it is called, it will be called with the right
context and it will not change the result in a promise chain.