listr 

> Terminal task list

Install

``
$ npm install --save listr
`

Usage

`js
const execa = require('execa');
const Listr = require('listr');

const tasks = new Listr([
{
title: 'Git',
task: () => {
return new Listr([
{
title: 'Checking git status',
task: () => execa.stdout('git', ['status', '--porcelain']).then(result => {
if (result !== '') {
throw new Error('Unclean working tree. Commit or stash changes first.');
}
})
},
{
title: 'Checking remote history',
task: () => execa.stdout('git', ['rev-list', '--count', '--left-only', '@{u}...HEAD']).then(result => {
if (result !== '0') {
throw new Error('Remote history differ. Please pull changes.');
}
})
}
], {concurrent: true});
}
},
{
title: 'Install package dependencies',
task: () => execa('npm', ['install'])
},
{
title: 'Run tests',
task: () => execa('npm', ['test'])
},
{
title: 'Publish package',
task: () => execa('npm', ['publish'])
}
]);

tasks.run().catch(err => {
console.error(err);
});
`

$3

A task can return different values. If a task returns, it means the task was completed successfully. If a task throws an error, the task failed.

`js
const tasks = new Listr([
{
title: 'Success',
task: () => 'Foo'
},
{
title: 'Failure',
task: () => {
throw new Error('Bar')
}
}
]);
`


#### Promises

A task can also be async by returning a Promise. If the promise resolves, the task completed successfully, it it rejects, the task failed.

`js
const tasks = new Listr([
{
title: 'Success',
task: () => Promise.resolve('Foo')
},
{
title: 'Failure',
task: () => Promise.reject('Bar')
}
]);
`

#### Observable

A task can also return an Observable. The thing about observables is that it can emit multiple values and can be used to show the output of the
task. Please note that only the last line of the output is rendered.

`js
const tasks = new Listr([
{
title: 'Success',
task: () => {
return new Observable(observer => {
observer.next('Foo');

setTimeout(() => {
observer.next('Bar');
}, 2000);

setTimeout(() => {
observer.complete();
}, 4000);
});
}
},
{
title: 'Failure',
task: () => Promise.reject(new Error('Bar'))
}
]);
`

#### Streams

It's also possible to return a stream. The stream will be converted to an Observable and handled as such.


#### Skipping tasks

Optionally specify a skip function to determine whether a task can be skipped.

- If the skip function returns a truthy value or a Promise that resolves to a truthy value then the task will be skipped.
- If the returned value is a string it will be displayed as the reason for skipping the task.
- If the skip function returns a falsey value or a Promise that resolves to a falsey value then the task will be executed as normal.
- If the skip function throws or returns a Promise that rejects, the task (and the whole build) will fail.

`js
const tasks = new Listr([
{
title: 'Task 1',
task: () => Promise.resolve('Foo')
},
{
title: 'Can be skipped',
skip: () => {
if (Math.random() > 0.5) {
return 'Reason for skipping';
}
},
task: () => 'Bar'
},
{
title: 'Task 3',
task: () => Promise.resolve('Bar')
}
]);
`

API

$3

#### tasks

Type: object[]

List of tasks.

##### title

Type: string

Title of the task.

##### task

Type: Function

Task function.

##### skip

Type: Function

Skip function. Read more about skipping tasks.

#### options

##### showSubtasks

Type: boolean

Default: true

Set to false if you want to disable the rendering of the subtasks. Subtasks will be rendered if
an error occurred in one of them.

##### concurrent

Type: boolean

Default: false

Set to true if you want tasks to run concurrently.

$3

#### add(task)

Returns the instance.

##### task

Type: object object[]`

Task object or multiple task objects.

#### run()

Start executing the tasks.

Related

- ora - Elegant terminal spinner
- cli-spinners - Spinners for use in the terminal

License

MIT © Sam Verschueren