d-queue

A DebounceQueue debounces functions to run only when a queue is idle.

Create a DebounceQueue:

import dq from '@zuze/d-queue';
...
const { run, queue, dequeue } = dq(argumentProcessor);

Add a function to be run when the queue is idle:

queue(fnToBeRun,arguments)

If the queue is not busy, this function will be run immediately. To make a queue busy, call run with a synchronous or asynchronous function. No functions added to the queue while it is busy will be called. After the queue becomes idle, all existing queued functions will be flushed.

Why?

A DebounceQueue is highly useful for subscription-style callbacks that you do not want to get called while other things are happening.

What's an argument processor?

In the case of subscriptions, the same function reference is typically added to a DebounceQueue between flushes. An argument processor is a function that accepts the current arguments the queued function should be flushed with and the last arguments the function was flushed with and returns an array of new arguments. The default argument processor is the identity function

Example

const { run,  queue } = dq();
something.subscribe(() => run(async () => await doSomethingElse()))
const debounceSubscriptionManager = fn => somethingElse.subscribe((...args) => queue(fn,args))

The purpose of this is to allow subscriptions to be added to somethingElse that will not get called if doSomethingElse is running.

When something calls a callback, it will call the asynchronous function doSomethingElse. Any existing or new subscriptions to somethingElse will not be run until doSomethingElse has completed.

API

const { queue, dequeue, run } = dq(argumentProcessor: (nextArgs = [], lastArgs = []) => any[])

Creates a new debounce queue. Returns queue, dequeue, and run functions.

• queue (fn: Function, args?: any[]) Accepts a function reference and (optionally) an array arguments that function should be called with. The function is run when the queue becomes idle.

• dequeue (fn: Function) Removes a function reference from the queue.

• run( done? => void | Promise ) Starts a process running. Any functions added to the queue will the process is running will not be run until the process is complete. It can be made async by either returning a promise or calling the done function passed to the callback as an argument.

Returning a promise and accepting a done parameter are mutually exclusive. If the callback function accepts a done parameter, it must be called.