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https://github.com/kgryte/utils-series-waterfall
Invoke functions in series, passing the results of one function as arguments to the next function.
https://github.com/kgryte/utils-series-waterfall
Last synced: 25 days ago
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Invoke functions in series, passing the results of one function as arguments to the next function.
- Host: GitHub
- URL: https://github.com/kgryte/utils-series-waterfall
- Owner: kgryte
- License: mit
- Created: 2016-02-18T06:29:22.000Z (over 8 years ago)
- Default Branch: master
- Last Pushed: 2016-02-18T10:03:48.000Z (over 8 years ago)
- Last Synced: 2024-10-05T07:47:38.950Z (about 1 month ago)
- Language: JavaScript
- Size: 18.6 KB
- Stars: 3
- Watchers: 3
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
Waterfall
===
[![NPM version][npm-image]][npm-url] [![Build Status][build-image]][build-url] [![Coverage Status][coverage-image]][coverage-url] [![Dependencies][dependencies-image]][dependencies-url]
> Invoke functions in series, passing the results of one function as arguments to the next function.
## Installation
``` bash
$ npm install utils-series-waterfall
```
## Usage
``` javascript
var waterfall = require( 'utils-series-waterfall' );
```
#### waterfall( fcns, clbk[, thisArg] )
Invokes `functions` in series, passing the results of one `function` as arguments to the next `function`.
``` javascript
function foo( next ) {
next( null, 'beep' );
}
function bar( str, next ) {
console.log( str );
// => 'beep'
next();
}
function done( error ) {
if ( error ) {
throw error;
}
}
var fcns = [ foo, bar ];
waterfall( fcns, done );
```
To set the `this` context for __all__ `functions`, provide a `thisArg`.
``` javascript
function foo( next ) {
this._idx = 0;
next( null, 'beep' );
}
function bar( str, next ) {
this._idx += 1;
console.log( str );
// => 'beep'
next();
}
function done( error ) {
if ( error ) {
throw error;
}
console.log( ctx._idx );
// => 1
}
var ctx = {};
var fcns = [ foo, bar ];
waterfall( fcns, done, ctx );
```
#### waterfall.factory( fcns, done[, thisArg] )
Returns a reusable waterfall `function`.
``` javascript
var run = waterfall.factory( fcns, done );
// returns
run();
run();
run();
// ...
```
## Notes
* The last `argument` applied to each waterfall `function` is a callback. This `function` should be invoked upon a series `function` completion. The first argument is reserved as an `error` argument (which can be `null`). Any results which should be passed to the next `function` in the series should be provided beginning with the second argument.
* If any `function` calls the provided callback with a truthy `error` argument, the waterfall suspends execution and immediately calls the `done` callback for subsequent `error` handling.
* This implementation does __not__ guarantee that execution is asynchronous. To do so, wrap the `done` callback in a `function` which either executes at the end of the current stack (e.g., `nextTick`) or during a subsequent turn of the event loop (e.g., `setIntermediate`, `setTimeout`).
## Examples
``` javascript
var waterfall = require( 'utils-series-waterfall' );
function foo( next ) {
next( null, 'beep' );
}
function bar( str, next ) {
console.log( str );
next( null, str.replace( /e/g, 'o' ) );
}
function fun( str, next ) {
console.log( str );
next();
}
function done( error ) {
if ( error ) {
throw error;
}
console.log( 'done' );
}
var fcns = [ foo, bar, fun ];
waterfall( fcns, done );
```
To run the example code from the top-level application directory,
``` bash
$ node ./examples/index.js
```
---
## Tests
### Unit
This repository uses [tape][tape] for unit tests. To run the tests, execute the following command in the top-level application directory:
``` bash
$ make test
```
All new feature development should have corresponding unit tests to validate correct functionality.
### Test Coverage
This repository uses [Istanbul][istanbul] as its code coverage tool. To generate a test coverage report, execute the following command in the top-level application directory:
``` bash
$ make test-cov
```
Istanbul creates a `./reports/coverage` directory. To access an HTML version of the report,
``` bash
$ make view-cov
```
### Browser Support
This repository uses [Testling][testling] for browser testing. To run the tests in a (headless) local web browser, execute the following command in the top-level application directory:
``` bash
$ make test-browsers
```
To view the tests in a local web browser,
``` bash
$ make view-browser-tests
```
---
## License
[MIT license](http://opensource.org/licenses/MIT).
## Copyright
Copyright © 2016. Athan Reines.
[npm-image]: http://img.shields.io/npm/v/utils-series-waterfall.svg
[npm-url]: https://npmjs.org/package/utils-series-waterfall
[build-image]: http://img.shields.io/travis/kgryte/utils-series-waterfall/master.svg
[build-url]: https://travis-ci.org/kgryte/utils-series-waterfall
[coverage-image]: https://img.shields.io/codecov/c/github/kgryte/utils-series-waterfall/master.svg
[coverage-url]: https://codecov.io/github/kgryte/utils-series-waterfall?branch=master
[dependencies-image]: http://img.shields.io/david/kgryte/utils-series-waterfall.svg
[dependencies-url]: https://david-dm.org/kgryte/utils-series-waterfall
[dev-dependencies-image]: http://img.shields.io/david/dev/kgryte/utils-series-waterfall.svg
[dev-dependencies-url]: https://david-dm.org/dev/kgryte/utils-series-waterfall
[github-issues-image]: http://img.shields.io/github/issues/kgryte/utils-series-waterfall.svg
[github-issues-url]: https://github.com/kgryte/utils-series-waterfall/issues
[tape]: https://github.com/substack/tape
[istanbul]: https://github.com/gotwarlost/istanbul
[testling]: https://ci.testling.com