# output-interceptor

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Intercepts stdout/ stderr.

## Implementation

This module uses [`domain`](https://nodejs.org/api/domain.html) to capture asynchronous function output.

Read [Capturing stdout/ stderr in Node.js using Domain module](https://medium.com/@gajus/capturing-stdout-stderr-in-node-js-using-domain-module-3c86f5b1536d).

## Usage

```js
import {
  createOutputInterceptor
} from 'output-interceptor';

const interceptOutput = createOutputInterceptor();

const main = async () => {
  const result = await interceptOutput(() => {
    console.log('foo');
    console.error('bar');

    return Promise.resolve('baz');
  });

  result === 'baz';

  interceptOutput.output === 'foo\nbar\n';
};

main();

```

## API

```js
/**
 * @property interceptStderr Default: true.
 * @property interceptStdout Default: true.
 * @property stripAnsi Default: true.
 */
export type OutputInterceptorUserConfigurationType = {|
  +interceptStderr?: boolean,
  +interceptStdout?: boolean,
  +stripAnsi?: boolean
|};

/**
 * @returns Intercepted output.
 */
type FlushType = () => string;

/**
 * @property output Output produced during the executing of the `routine`.
 */
export type OutputInterceptorType = {|
  <T>(routine: () => Promise<T> | T): Promise<T>,
  output: ''
|};

createOutputInterceptor(userConfiguration?: OutputInterceptorUserConfigurationType): OutputInterceptorType;

```