loilo-archive/node-promising-drain

A Node.js queue for executing Promise-returning asynchronous functions in order

Promising Drain

A little queue for executing Promise-returning asynchronous functions in order

Installation

Get it like:

npm install --save promising-drain

Usage

To chain functions, do this:

const Drain = require('promising-drain')

const drain = new Drain()

drain.pour(asyncFunction1)
drain.pour(asyncFunction2)

The drain will instantly start dripping and execute asyncFunction2 as soon as asynFunction1 finishes.

The pour() method also returns a promise that will resolve then the function has been executed and be rejected if it definitely won't (e.g. the queue is cleared beforehand).

Hint: Your functions are expected to return promises. They'll be wrapped in Promise.resolve though, meaning that you can also use synchronous functions returning anything else if you need to.

Pause / resume the drain

You can cork the drain to prevent queued functions from running.

drain.cork()

And uncork it to resume.

drain.uncork()

Clear the drain

Flush all functions from the drain:

drain.clear()

Get queue information

Check the number of remaining functions in the drain:

drain.remaining.length === someNumber

See if the drain is currently corked:

drain.corked === true

Events

This module emits some events that may be listened to via the infamous .on(), .once() and .off() method.

drip

The module fires a drip event whenever the currently executed function finishes.

The parameter passed to the listeners will be an object containing a result property that is the resolved result of the function.

error

An error event gets emitted when a function in the drain throws an exception.

The exception object will be passed as a parameter to listener functions.

drained

When the queue is empty, a drained event is triggered.

cork

The cork event is fired whenever the drain is being corked.

uncork

The uncork event is triggered when the drain gets uncorked.