taskr 

Taskr is a highly performant task automation tool, much like Gulp or Grunt, but written with concurrency in mind. With Taskr, everything is a coroutine, which allows for cascading and composable tasks; but unlike Gulp, it's not limited to the stream metaphor.

Taskr is extremely extensible, so _anything_ can be a task. Our core system will accept whatever you throw at it, resulting in a modular system of reusable plugins and tasks, connected by a declarative taskfile.js that's easy to read.

Table of Contents

Features

- lightweight: with 6 dependencies, installation takes seconds
- minimal API: Taskr only exposes a couple methods, but they're everything you'll ever need
- performant: because of Bluebird, creating and running Tasks are quick and inexpensive
- cascading: sequential Task chains can cascade their return values, becoming the next Task's argument
- asynchronous: concurrent Task chains run without side effects & can be yielded consistently
- composable: chain APIs and Tasks directly; say goodbye to pipe() x 100!
- modular: easily share or export individual Tasks or Plugins for later use
- stable: requires Node >= 4.6 to run (LTS is 6.11)

Example

Here's a simple taskfile (with shorthand generator methods) depicting a parallel chain.

``js
const sass = 'src/{admin,client}/*.sass';
const js = 'src/{admin,client}/*.js';
const dist = 'build';

module.exports = {
*lint(task) {
yield task.source(js).xo({ esnext:true });
},
*scripts(task) {
yield task.source(js).babel({ presets:['es2015'] }).target(${dist}/js);
},
*styles(task) {
yield task.source(sass).sass({ outputStyle:'compressed' }).autoprefixer().target(${dist}/css);
},
*build(task) {
yield task.parallel(['lint', 'scripts', 'styles']);
}
}
`

Concepts

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Taskr is a task runner. It's designed to get you from A to B -- that's it.

If it helps, imagine you're dining in a restaurant and Taskr is the food runner. Taskr's role is solely to collect meals from the kitchen (task.source) and deliver them to the correct table (task.target). As a food runner, Taskr may do this one plate at a time (task.serial) or deliver multiple plates at once (task.parallel). Either way, Taskr only cares about going from A to B. It may not be the most glamorous job, but as far as you (the patron) are concerned, it's incredibly important because it brings you food.

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Because Taskr is single-minded and cares only about executing tasks, everything else is a plugin. This keeps development with Taskr easy, approachable, and lightweight.

You see, installing Taskr gives access to a reliable task runner. You decide what it _can do_, provide it functionality, and dictate when to do it. You're in full control.

Through plugins, you are able to capture useful behavior and share them across tasks or projects for repeated use. Plugins come in three flavors:

* external - installed via NPM; called "external" because they live outside your codebase
* inline - generally simple, one-time functions; not sensible for reuse since declared within a task (hence "inline")
* local - private, reusable plugins; appear exactly like external plugins but not public on NPM.

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Tasks are used to tell Taskr what to do. They are written as generator functions & converted to coroutines internally. They're also fully self-contained and, like plugins, can be shared across projects if desired.

Upon runtime, tasks are cheap to create, so are also destroyed once completed. This also helps Taskr remain efficient; history won't weigh it down.

Lastly, tasks have the power to start other Tasks, including serial and parallel chains!

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Much like Gulp, Taskr uses a taskfile.js (case sensitive) to read and run your Tasks. However, because it's a regular JavaScript file, you may also require() additional modules and incorporate them directly into your Tasks, without the need for a custom Plugin!

`js
const browserSync = require('browser-sync');

exports.serve = function * (task) {
browserSync({
port: 3000,
server: 'dist',
middleware: [
require('connect-history-api-fallback')()
]
});
yield task.$.log('> Listening on localhost:3000');
}
`

Taskfiles should generally be placed in the root of your project, alongside your package.json. Although this is not required, Taskr (strongly) prefers this location.

> Note: You may set an alternate directory path through the CLI's cwd option.

Through Node, Taskr only supports ES5 syntax; however, if you prefer ES6 or ES7, just install @taskr/esnext!

CLI

Taskr's CLI tool is very simple and straightforward.

`
taskr [options]
taskr --mode=parallel task1 task2 ...
`
> Please run taskr --help or taskr -h for usage information.

Most commonly, the CLI is used for NPM script definitions.

`js
// package.json
{
"scripts": {
"build": "taskr foo bar"
}
}
`

API

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Taskr itself acts as a "parent" class to its Task children. Because of this, Taskr's methods are purely executive; aka, they manage Tasks and tell them how & when to run.

#### Taskr.start(task, [options])
Yield: Any

Start a Task by its name; may also pass initial values. Can return anything the Task is designed to.

##### task
Type: String

Default: 'default'

The Task's name to run. Task must exist/be defined or an Error is thrown.

> Important! Taskr expects a default task if no task is specified. This also applies to CLI usage.

##### options
Type: Object

Default: { src:null, val:null }

Initial/Custom values to start with. You may customize the object shape, but only val will be cascaded from Task to Task.

#### Taskr.parallel(tasks, [options])
Yield: Any

Run a group of tasks simultaneously. Cascading is disabled.
##### tasks
Type: Array

The names of Tasks to run. Task names must be strings and must be defined.
##### options
Type: Object

Initial values to start with; passed to each task in the group. Does not cascade.

#### Taskr.serial(tasks, [options])
Yield: Any

Run a group of tasks sequentially. Cascading is enabled.
##### tasks
Type: Array

The names of Tasks to run. Task names must be strings and must be defined.
##### options
Type: Object

Initial values to start with; passed to each task in the group. Does cascade.

`js
module.exports = {
*default(task) {
yield task.serial(['first', 'second'], { val:10 });
},
*first(task, opts) {
yield task.$.log(first: ${opts.val});
return opts.val * 4;
},
*second(task, opts) {
yield task.$.log(second: ${opts.val});
return opts.val + 2;
}
}

const output = yield task.start();
//=> first: 10
//=> second: 40
console.log(output);
//=> 42
`

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Plugins can be external, internal, or local. However, all plugins share the same options:

##### options.every
Type: Boolean

Default: true

If the plugin function should iterate through _every_ file|glob.

##### options.files
Type: Boolean

Default: true

If the plugin should receive the Task's glob patterns or its expanded file objects. Uses globs if false.

Every plugin must also pass a generator function, which will be wrapped into a coroutine. This function's arguments will be the file|glob(s), depending on the options.every and options.files combination. The function's second argument is the user-provided config object.

The plugin's generator function is always bound to the current Task, which means this refers to the Task instance.

#### Internal Plugins

Internal plugins are for single-use only. If you're defining the same behavior repeatedly, it should be extracted to a local or external plugin instead.

> Note: Inline plugins have no need for a second argument in their generator function; you are the "user" here.

See task.run for a simple example. The same inline example may be written purely as an object:

`js
exports.foo = function * (task) {
yield task.source('src/*.js').run({
every: false,
*func(files) {
Array.isArray(files); //=> true
yield Promise.resolve('this will run once.');
}
}).target('dist');
}
`

#### External Plugins

Unlike "inline" plugins, external and local plugins are defined before a Task is performed. Because of this, they must define a name for their method to use within a Task.

Similar to inline plugins, there are two ways of defining an exported module -- via functional or object definitions.

When using a _functional definition_, the definition receives the Taskr instance and the utilities object.

`js
module.exports = function (task, utils) {
// promisify before running else repeats per execution
const render = utils.promisify(function () {});
// verbose API
task.plugin('myName', {every: false}, function * (files, opts) {
console.log('all my files: ', files); //=> Array
console.log(this._.files === files); //=> true
console.log(this instanceof Task); //=> true
console.log('user options: ', opts);
yield render(opts);
});
// or w/condensed API
task.plugin({
name: 'myName',
every: false,
*func(files, opts) {
// ...same
}
});
}
`

When using an _object definition_, you are not provided the task or utils parameters. This assumes that you do not need any prep work for your plugin!

`js
module.exports = {
name: 'myName',
every: false,
*func(files, opts) {
// do stuff
}
}
`

Then, within your Task, you may use it like so:

`js
exports.default = function * (task) {
yield task.source('src/*.js').myName({ foo:'bar' }).target('dist');
}
`

#### Local Plugins

Local plugins are defined exactly like external plugins. The only difference is that they're not installable via NPM.

In order to use a local plugin, add a taskr key to your package.json file. Then define a requires array with paths to your plugins.

`js
{
"taskr": {
"requires": [
"./build/custom-plugin-one.js",
"./build/custom-plugin-two.js"
]
}
}
`

For programmatic usage, simply pass an array of definitions to the plugins key:

`js
const Taskr = require('taskr')
const taskr = new Taskr({
plugins: [
require('./build/custom-plugin-one.js'),
require('./build/custom-plugin-two.js'),
require('@taskr/clear')
{
name: 'plugThree',
every: false,
files: false,
*func(globs, opts) {
// nifty, eh?
}
}
]
});
`

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A Task receives itself as its first argument. We choose to name the parameter task simply as a convention; of course, you may call it whatever you'd like.

Tasks are exported from a taskfile.js, which means you can use either syntax:

`js
exports.foo = function * (task) {
yield task.source('src/*.js').target('dist/js');
}
exports.bar = function * (task) {
yield task.source('src/*.css').target('dist/css');
}
// or
module.exports = {
*foo(task) {
yield task.source('src/*.js').target('dist/js');
},
*bar(task) {
yield task.source('src/*.css').target('dist/css');
}
}
`

Each Task also receives an opts object, consisting of src and val keys. Although src is primarily used for @taskr/watch, the val key can be used or set at any time see Taskr.serial.

All methods and values below are exposed within a Task's function.

#### task.root
Type: String

The directory wherein taskfile.js resides, now considered the root. Also accessible within plugins.

#### task.$
Type: Object

The Task's utility helpers. Also accessible within plugins. See Utilities.

#### task._
Type: Object

The Task's internal state, populated by task.source(). Also accessible within plugins.
##### task._.files
Type: Array

The Task's active files. Each object contains a dir and base key from its pathObject and maintains the file's Buffer contents as a data key.
##### task._.globs
Type: Array

The Task's glob patterns, from task.source(). Used to populate task._.files.
##### task._.prevs
Type: Array

The Task's last-known (aka, outdated) set of glob patterns. Used only for @taskr/watch.

#### task.source(globs, [options])
##### globs
Type: Array|String

Any valid glob pattern or array of patterns.
##### options
Type: Object

Default: {}

Additional options, passed directly to node-glob.

#### task.target(dirs, [options])
##### dirs
Type: Array|String

The destination folder(s).
##### options
Type: Object

Default: {}

Additional options, passed directly to fs.writeFile.

Please note that task.source() glob ambiguity affects the destination structure.

`js
yield task.source('src/*.js').target('dist');
//=> dist/foo.js, dist/bar.js
yield task.source('src/*/.js').target('dist');
//=> dist/foo.js, dist/bar.js, dist/sub/baz.js, dist/sub/deep/bat.js
`

#### task.run(options, generator)
Perform an inline plugin.

##### options
Type: Object

The See plugin options.
##### generator
Type: Function

The action to perform; must be a Generator function.

`js
exports.foo = function * (task) {
yield task.source('src/.js').run({ every:false }, function (files) {
Array.isArray(files); //=> true
yield Promise.resolve('this will run once.');
}).target('dist')
}
`

#### task.start(task, [options])
See Taskr.start.

#### task.parallel(tasks, [options])
See Taskr.parallel.

#### task.serial(tasks, [options])
See Taskr.serial.

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A collection of utility helpers to make life easy.

#### alert(...msg)
Print to console with timestamp and alert coloring. See utils.log.
##### msg
Type: String

#### coroutine(generator)
See Bluebird.coroutine.

#### error(...msg)
Print to console with timestamp and error coloring. See utils.log.
##### msg
Type: String

#### expand(globs, options)
Yield: Array

Get all filepaths that match the glob pattern constraints.
##### globs
Type: Array|String
##### options
Type: Object

Default: {}

Additional options, passed directly to node-glob.

#### find(filename, dir)
Yield: String|null

Find a complete filepath from a given path, or optional directory.
##### filename
Type: String

The file to file; may also be a complete filepath.
##### dir
Type: String

Default: '.'

The directory to look within. Will be prepended to the filename value.

#### log(...msg)
Print to console with timestamp and normal coloring.
##### msg
Type: String

You may pass more than one msg string.

`js
utils.log('Hello');
//=> [10:51:04] Hello
utils.log('Hello', 'World');
//=> [10:51:14] Hello World
`

#### promisify(function, callback)
See Bluebird.promisify.

#### read(filepath, options)
Yield: Buffer|String|null

Get a file's contents. Ignores directory paths.
##### filepath
Type: String

The full filepath to read.
##### options
Type: Object

Additional options, passed to fs.readFile.

#### trace(stack)
Parse and prettify an Error's stack.

#### write(filepath, data, options)
Yield: null

Write given data to a filepath. Will create directories as needed.
##### filepath
Type: String

The full filepath to write into.
##### data
Type: String|Buffer

The data to be written; see fs.writeFile.
##### options
Type: Object

Additional options, passed to fs.writeFile.

Installation

`sh
$ npm install --save-dev taskr
`

Usage

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1. Install Taskr & any desired plugins. (see installation and ecosystem)
2. Create a taskfile.js next to your package.json.
3. Define default and additional tasks within your taskfile.js.

`js
exports.default = function * (task) {
yield task.parallel(['styles', 'scripts']);
}

exports.styles = function * (task) {
yield task.source('src/*/.css').autoprefixer().target('dist/css');
}

exports.scripts = function * (task) {
yield task.source('src/*/.js').babel({
presets: [
['es2015', { loose:true, modules:false }]
]
}).target('dist/js');
}
`
4. Add a "scripts" key to your package.json:

`json
{
"name": "my-project",
"scripts": {
"build": "taskr"
}
}
`

> Note: The default task is run if no other tasks are specified.
5. Run your build command:

`sh
$ npm run build
`

You may be interested in checking out Web Starter Kit for a head start.

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Taskr is extremely flexible should you choose to use Taskr outside of its standard configuration.

The quickest path to a valid Taskr instance is to send a tasks object:

`js
const Taskr = require('Taskr');
const taskr = new Taskr({
tasks: {
*foo(f) {},
*bar(f) {}
}
});
taskr.start('foo');
`

By default, your new Taskr instance will not include any plugins. You have the power to pick and choose what your instance needs!

To do this, you may pass an array of external and local plugins:

`js
const taskr = new Taskr({
plugins: [
require('@taskr/concat'),
require('@taskr/clear'),
require('./my-plugin')
]
});
`

> Important: This assumes you have provided a valid file _or_ tasks object. Without either of these, your Taskr instance will be incomplete and therefore invalid. This will cause the instance to exit early, which means that your plugins will not be mounted to the instance.

You may also define your tasks by supplying a taskfile.js path to file. Whenever you do this, you should also update the cwd key because your root has changed!

`js
const join = require('path').join;

const cwd = join(__dirname, '..', 'build');
const file = join(cwd, 'taskfile.js');

const taskr = new Taskr({ file, cwd });
`

Credits

This project used to be called fly, but Jorge Bucaran, its original author, generously handed over the project to Luke Edwards in order to further development. The project is now named taskr to reflect the transition and its exicitng new future!

A big thanks to Constantin Titarenko for donating the name taskr` on NPM -- very much appreciated!