Infinite Queue

A small library which implements a queue where you are able to request items early if the queue is empty.

Installation

npm install --save infinite-queue

or available on JSDelivr at "https://cdn.jsdelivr.net/npm/infinite-queue@1".

API

InfiniteQueue<TItem>()

Create a queue.

queue.push(item: TItem): void

Push an item onto the queue.

queue.next(): Promise<TItem>

Returns a promise that will resolve with the oldest item in the queue, when there is one.

queue.next<TReturn>(onItem (item: TItem) => TReturn): Promise<TReturn>

Provide an onItem callback which will be called immediately if there is already an item in the queue, or synchronously from the next push() call.

The promise returned from next() will resolve with whatever you return from onItem.

Use queue.next() unless you need to be notified synchronously.

queue.numItems()

Returns the number of items remaining in the queue.

queue.reset()

Clears the queue and rejects any pending next() promises with queueResetError.

Example

import { InfiniteQueue } from 'infinite-queue';

const queue = InfiniteQueue<string>();

queue.push('a');
console.log('pushed 1');
setTimeout(() => {
  queue.push('b');
  queue.push('c');
  console.log('pushed 2 and 3');
}, 1000);

console.log('waiting for 1');
console.log('got 1', await queue.next()));
console.log('waiting for 2');
console.log('got 2', await queue.next()));
console.log('waiting for 3');
console.log('got 3', await queue.next()));

This would output:

pushed 1
waiting for 1
got 1 a
waiting for 2
pushed 2 and 3
got 2 b
got 3 c