composer     

> Run and compose async tasks. Easily define groups of tasks to run in series or parallel.

Please consider following this project's author, Brian Woodward, and consider starring the project to show your :heart: and support.

- Install
- Usage
- API
* Tasks
* Generators
- Events
* task
* task-pending
* task-preparing
- Release history
- About

_(TOC generated by verb using markdown-toc)_

Install

Install with npm:

``sh
$ npm install --save composer
`

Usage

`js
// Create an instance of Composer
const Composer = require('composer');
const composer = new Composer();

// Define tasks with the .task() method
composer.task('foo', callback => {
callback(); // do stuff
});
composer.task('bar', callback => {
callback(); // do stuff
});

composer.task('baz', ['foo'. 'bar']);

// Run tasks with the .build() method
composer.build('baz')
.then(() => console.log('done!'))
.catch(console.error);
`

API

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Factory for creating a custom Tasks class that extends the given Emitter. Or, simply call the factory function to use the built-in emitter.

Params

* Emitter {function}: Event emitter.
* returns {Class}: Returns a custom Tasks class.

Example

`js
// custom emitter
const Emitter = require('events');
const Tasks = require('composer/lib/tasks')(Emitter);
// built-in emitter
const Tasks = require('composer/lib/tasks')();
const composer = new Tasks();
`

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Create an instance of Tasks with the given options.

Params

* options {object}

Example

`js
const Tasks = require('composer').Tasks;
const composer = new Tasks();
`

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Define a task. Tasks run asynchronously, either in series (by default) or parallel (when options.parallel is true). In order for the build to determine when a task is complete, _one of the following_ things must happen: 1) the callback must be called, 2) a promise must be returned, or 3) a stream must be returned. Inside tasks, the "this" object is a composer Task instance created for each task with useful properties like the task name, options and timing information, which can be useful for logging, etc.

Params

* name {String}: The task name.
* deps {Object|Array|String|Function}: Any of the following: task dependencies, callback(s), or options object, defined in any order.
* callback {Function}: (optional) If the last argument is a function, it will be called after all of the task's dependencies have been run.
* returns {undefined}

Example

`js
// 1. callback
app.task('default', cb => {
// do stuff
cb();
});
// 2. promise
app.task('default', () => {
return Promise.resolve(null);
});
// 3. stream (using vinyl-fs or your stream of choice)
app.task('default', function() {
return vfs.src('foo/*.js');
});
`

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Run one or more tasks.

Params

* tasks {object|array|string|function}: One or more tasks to run, options, or callback function. If no tasks are defined, the default task is automatically run.
* callback {function}: (optional)
* returns {undefined}

Example

`js
const build = app.series(['foo', 'bar', 'baz']);
// promise
build().then(console.log).catch(console.error);
// or callback
build(function() {
if (err) return console.error(err);
});
`

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Compose a function to run the given tasks in series.

Params

* tasks {object|array|string|function}: Tasks to run, options, or callback function. If no tasks are defined, the default task is automatically run, if one exists.
* callback {function}: (optional)
* returns {promise|undefined}: Returns a promise if no callback is passed.

Example

`js
const build = app.series(['foo', 'bar', 'baz']);
// promise
build().then(console.log).catch(console.error);
// or callback
build(function() {
if (err) return console.error(err);
});
`

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Compose a function to run the given tasks in parallel.

Params

* tasks {object|array|string|function}: Tasks to run, options, or callback function. If no tasks are defined, the default task is automatically run, if one exists.
* callback {function}: (optional)
* returns {promise|undefined}: Returns a promise if no callback is passed.

Example

`js
// call the returned function to start the build
const build = app.parallel(['foo', 'bar', 'baz']);
// promise
build().then(console.log).catch(console.error);
// callback
build(function() {
if (err) return console.error(err);
});
// example task usage
app.task('default', build);
`

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Static method for creating a custom Tasks class with the given Emitter.

Params

* Emitter {Function}
* returns {Class}: Returns the custom class.

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Static factory method for creating a custom Composer class that extends the given Emitter.

Params

* Emitter {Function}: Event emitter.
* returns {Class}: Returns a custom Composer class.

Example

``js
// Composer extends a basic event emitter by default
const Composer = require('composer');
const composer = new Composer();

// Create a custom Composer class with your even emitter of choice
const Emitter = require('some-emitter');
const CustomComposer = Composer.create(Emitter);
const composer = new CustomComposer();
`

Params

* name {String}
* options {Object}
* returns {Object}: Returns an instance of Composer.

Example

`js
const composer = new Composer();
`

Create a wrapped generator function with the given name, config, and fn.

Params

* name {String}
* config {Object}: (optional)
* fn {Function}
* returns {Function}

Returns true if the given value is a Composer generator object.

Params

* val {Object}
* returns {Boolean}

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Alias to .setGenerator.

Params

* name {String}: The generator's name
* options {Object|Function|String}: or generator
* generator {Object|Function|String}: Generator function, instance or filepath.
* returns {Object}: Returns the generator instance.

Example

`js
app.register('foo', function(app, base) {
// "app" is a private instance created for the generator
// "base" is a shared instance
});
`

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Get and invoke generator name, or register generator name with the given val and options, then invoke and return the generator instance. This method differs from .register, which lazily invokes generator functions when .generate is called.

Params

* name {String}
* fn {Function|Object}: Generator function, instance or filepath.
* returns {Object}: Returns the generator instance or undefined if not resolved.

Example

`js
app.generator('foo', function(app, options) {
// "app" - private instance created for generator "foo"
// "options" - options passed to the generator
});
`

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Store a generator by file path or instance with the given name and options.

Params

* name {String}: The generator's name
* options {Object|Function|String}: or generator
* generator {Object|Function|String}: Generator function, instance or filepath.
* returns {Object}: Returns the generator instance.

Example

`js
app.setGenerator('foo', function(app, options) {
// "app" - new instance of Generator created for generator "foo"
// "options" - options passed to the generator
});
`

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Get generator name from app.generators, same as [findGenerator], but also invokes the returned generator with the current instance. Dot-notation may be used for getting sub-generators.

Params

* name {String}: Generator name.
* returns {Object|undefined}: Returns the generator instance or undefined.

Example

`js
const foo = app.getGenerator('foo');

// get a sub-generator
const baz = app.getGenerator('foo.bar.baz');
`

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Find generator name, by first searching the cache, then searching the cache of the base generator. Use this to get a generator without invoking it.

Params

* name {String}
* options {Function}: Optionally supply a rename function on options.toAlias
* returns {Object|undefined}: Returns the generator instance if found, or undefined.

Example

`js
// search by "alias"
const foo = app.findGenerator('foo');

// search by "full name"
const foo = app.findGenerator('generate-foo');
`

Params

* name {String}
* returns {Boolean}

Example

`js
console.log(app.hasGenerator('foo'));
console.log(app.hasGenerator('foo.bar'));
`

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Run one or more tasks or sub-generators and returns a promise.

Params

* name {String}
* tasks {String|Array}
* returns {Promise}

Events

* emits: generate with the generator name and the array of tasks that are queued to run.

Example

`js
// run tasks bar and baz on generator foo
app.generate('foo', ['bar', 'baz']);

// or use shorthand
app.generate('foo:bar,baz');

// run the default task on generator foo
app.generate('foo');

// run the default task on the default generator, if defined
app.generate();
`

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Create a generator alias from the given name. By default, generate- is stripped from beginning of the generator name.

Params

* name {String}
* options {Object}
* returns {String}: Returns the alias.

Example

`js
// customize the alias
const app = new Generate({ toAlias: require('camel-case') });
`

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Returns true if every name in the given array is a registered generator.

Params

* names {Array}
* returns {Boolean}

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Format task and generator errors.

Params

* name {String}
* returns {Error}

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Disable inspect. Returns a function to re-enable inspect. Useful for debugging.

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Get the first ancestor instance of Composer. Only works if generator.parent is
defined on child instances.

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Get or set the generator name.

Params

* {String}

* returns {String}

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Get or set the generator alias. By default, the generator alias is created
by passing the generator name to the .toAlias method.

Params

* {String}

* returns {String}

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Get the generator namespace. The namespace is created by joining the generator's alias
to the alias of each ancestor generator.

Params

* {String}

* returns {String}

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Get the depth of a generator - useful for debugging. The root generator
has a depth of 0, sub-generators add 1 for each level of nesting.

* returns {Number}

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Static method that returns a function for parsing task arguments.

Params

* register {Function}: Function that receives a name of a task or generator that cannot be found by the parse function. This allows the register function to dynamically register tasks or generators.
* returns {Function}: Returns a function for parsing task args.

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Static method that returns true if the given val is an instance of Generate.

Params

* val {Object}
* returns {Boolean}

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Static method for creating a custom Composer class with the given Emitter.

Params

* Emitter {Function}
* returns {Class}: Returns the custom class.

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Static getter for getting the Tasks class with the same Emitter class as Composer.

Params

* Emitter {Function}
* returns {Class}: Returns the Tasks class.

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Static getter for getting the Task class.

Example

``js
const { Task } = require('composer');
`

Events

$3

`js
app.on('task', function(task) {
switch (task.status) {
case 'starting':
// Task is running
break;
case 'finished':
// Task is finished running
break;
}
});
`

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Emitted after a task is registered.

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Emitted when a task is preparing to run, right before it's called. You can use this event to dynamically skip tasks by updating task.skip to true or a function.

Release history

See the changelog.

About

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| Commits | Contributor |
| --- | --- |
| 227 | doowb |
| 72 | jonschlinkert |

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Brian Woodward

* GitHub Profile
* Twitter Profile
* LinkedIn Profile

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Copyright © 2018, Brian Woodward.
Released under the MIT License.

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_This file was generated by verb-generate-readme, v0.8.0, on November 11, 2018._