SimpleQueue

A simple FIFO queue

npm install SimpleQueue

What is this?

There are plenty queues for node, but even those branded as FIFO (first in first out) usually destroy the order.
Eg. when mapping over an RSS feeds & doing something with all of the pages,
you need to know what element had what position - so I created this little helper.

API

$3

A simple FIFO queue, delivering items in order.

#### Type parameters

| Name | Default | Description |
| ---- | ------- | ---------------------------------------- |
| T | - | Type that is pushed onto the stack. |
| R | void | Type that the passed callback maps to. |

$3

#### constructor

\+ new SimpleQueue(worker: (element: T, callback: (error: Error \| null, result: R) => void) => void, callback: (error: Error \| null, result: R, element: T) => void, done?: undefined \| () => void, concurrent?: number): SimpleQueue

_Defined in index.ts:16_

Creates a new FIFO queue.

##### Parameters:

| Name | Type | Default value | Description |
| ------------ | ------------------------------------------------------------------------- | ------------- | ---------------------------------------------------------- |
| worker | (element: T, callback: (error: Error \| null, result: R) => void) => void | - | Method to call for each child. Args: |
| callback | (error: Error \| null, result: R, element: T) => void | - | Method to call when an element was processed. |
| done? | undefined \| () => void | - | Method to call once the stack is cleared. |
| concurrent | number | 20 | Number of elements to process in parallel. Defaults to 20. |

Returns: SimpleQueue

$3

#### paused

• paused: boolean = false

_Defined in index.ts:16_

$3

#### abort

▸ abort(): void

_Defined in index.ts:48_

Clears the queue (can't stop running processes).

Returns: void

---

#### pause

▸ pause(): void

_Defined in index.ts:57_

Pause the queue execution.
Will not stop already in-flight items.

Returns: void

---

#### push

▸ push(props: T): void

_Defined in index.ts:41_

Adds an element to the queue.

##### Parameters:

| Name | Type |
| ------- | ---- |
| props | T |

Returns: void

---

#### resume

▸ resume(): void

_Defined in index.ts:64_

Resume the queue execution,
and catch up with remaining items.

Returns: void

Example

``js
import SimpleQueue from "SimpleQueue";

const queue = new SimpleQueue(
(element, callback) => {
// Set
setTimeout(() => callback(null, element / 1000), element);
},
(err, result, element) => {
console.log(result);
},
() => {
console.log("done");
},
4
);

queue.push(1000);
queue.push(5000);
queue.push(3000);
queue.push(4000);
queue.push(8000);
queue.push(2000);
queue.push(0);
``

Output:

1, 5, 3, 4, 8, 2, 0, "done"

This takes 9 seconds to run.