# gulp-function

accepts a function call as parameter to execute in gulp pipeline

## Availabililty

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## Status for master

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### Usage

```typescript
import gulp = require('gulp');
import gulpFunction from 'gulp-function'; // default ES6 export
// import {forFirst, forEach, atEnd} from 'gulp-function'

let myAsyncFunction = async (file, enc) => {
  // await some async stuff
};

gulp.task('gulpTest', function() {
  let stream = gulp
    .src('./mydir/*.something')
    .pipe(gulpFunction(myAsyncFunction, 'forEach')) //read the notes below
    // .pipe(forEach(myAsyncFunction)) // if imported as >> import { forEach } from 'gulp-function' <<
    .pipe(gulp.dest('./build/'));
  return stream; // by returning the stream gulp knows when our task has finished.
});
```

### Notes

- The first argument of gulpFunction can also be an **array of multiple functionnames**.
  Each function can return a promise. The pipe stop will finish when every promise is fullfilled.
  When providing an array of functions be careful with modifying the file object -> race condition
- The second argument can be empty, it defaults to "forEach"
- The following options are available:
  - "forFirst" - executes when first chunk/vinylfile of the stream reaches the pipestop.
    file is pushed further down the line when function's returned promise is fullfilled.
  - "forEach" - executes like "forFirst" but with every chunk/vinylfile in the stream;
  - "atEnd" - executes after all chunks have passed and are processed in full.
    That means the stream's "finish" event fires **before "atLast" is executed**!!!

For further information read the linked docs at the top of this README.

> MIT licensed | **&copy;** [Lossless GmbH](https://lossless.gmbh)
> | By using this npm module you agree to our [privacy policy](https://lossless.gmbH/privacy.html)

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