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Queuer

Class: Queuer<TValue>

Defined in: queuer.ts:243

A flexible queue that processes items with configurable wait times, expiration, and priority.

Features:

  • Automatic or manual processing of items
  • FIFO (First In First Out), LIFO (Last In First Out), or double-ended queue behavior
  • Priority-based ordering when getPriority is provided
  • Item expiration and removal of stale items
  • Callbacks for queue state changes, execution, rejection, and expiration

Running behavior:

  • start(): Begins automatically processing items in the queue (defaults to isRunning)
  • stop(): Pauses processing but maintains queue state
  • wait: Configurable delay between processing items
  • onItemsChange/onExecute: Callbacks for monitoring queue state

Manual processing is also supported when automatic processing is disabled:

  • execute(): Processes the next item using the provided function
  • getNextItem(): Removes and returns the next item without processing

Queue behavior defaults to FIFO:

  • addItem(item): Adds to the back of the queue
  • Items processed from the front of the queue

Priority queue:

  • Provide a getPriority function; higher values are processed first

Stack (LIFO):

  • addItem(item, 'back'): Adds to the back
  • getNextItem('back'): Removes from the back

Double-ended queue:

  • addItem(item, position): Adds to specified position ('front'/'back')
  • getNextItem(position): Removes from specified position

Item expiration:

  • expirationDuration: Maximum time items can stay in the queue
  • getIsExpired: Function to override default expiration
  • onExpire: Callback for expired items

State Management:

  • Uses TanStack Store for reactive state management
  • Use initialState to provide initial state values when creating the queuer
  • Use onExecute callback to react to item execution and implement custom logic
  • Use onItemsChange callback to react to items being added or removed from the queue
  • Use onExpire callback to react to items expiring and implement custom logic
  • Use onReject callback to react to items being rejected when the queue is full
  • The state includes execution count, expiration count, rejection count, and isRunning status
  • State can be accessed via queuer.store.state when using the class directly
  • When using framework adapters (React/Solid), state is accessed from queuer.state

Example usage:

ts
// Auto-processing queue with wait time
const autoQueue = new Queuer<number>((n) => console.log(n), {
  started: true, // Begin processing immediately
  wait: 1000, // Wait 1s between items
  onExecute: (item) => console.log(`Processed ${item}`)
});
autoQueue.addItem(1); // Will process after 1s
autoQueue.addItem(2); // Will process 1s after first item

// Manual processing queue
const manualQueue = new Queuer<number>((n) => console.log(n), {
  started: false
});
manualQueue.addItem(1); // [1]
manualQueue.addItem(2); // [1, 2]
manualQueue.execute(); // logs 1, queue is [2]
manualQueue.getNextItem(); // returns 2, queue is empty
// Auto-processing queue with wait time
const autoQueue = new Queuer<number>((n) => console.log(n), {
  started: true, // Begin processing immediately
  wait: 1000, // Wait 1s between items
  onExecute: (item) => console.log(`Processed ${item}`)
});
autoQueue.addItem(1); // Will process after 1s
autoQueue.addItem(2); // Will process 1s after first item

// Manual processing queue
const manualQueue = new Queuer<number>((n) => console.log(n), {
  started: false
});
manualQueue.addItem(1); // [1]
manualQueue.addItem(2); // [1, 2]
manualQueue.execute(); // logs 1, queue is [2]
manualQueue.getNextItem(); // returns 2, queue is empty

Type Parameters

• TValue

Constructors

new Queuer()

ts
new Queuer<TValue>(fn, initialOptions): Queuer<TValue>
new Queuer<TValue>(fn, initialOptions): Queuer<TValue>

Defined in: queuer.ts:250

Parameters

fn

(item) => void

initialOptions

QueuerOptions<TValue> = {}

Returns

Queuer<TValue>

Properties

options

ts
options: QueuerOptions<TValue>;
options: QueuerOptions<TValue>;

Defined in: queuer.ts:247


store

ts
readonly store: Store<Readonly<QueuerState<TValue>>>;
readonly store: Store<Readonly<QueuerState<TValue>>>;

Defined in: queuer.ts:244

Methods

addItem()

ts
addItem(
   item, 
   position, 
   runOnItemsChange): boolean
addItem(
   item, 
   position, 
   runOnItemsChange): boolean

Defined in: queuer.ts:364

Adds an item to the queue. If the queue is full, the item is rejected and onReject is called. Items can be inserted based on priority or at the front/back depending on configuration.

Returns true if the item was added, false if the queue is full.

Example usage:

ts
queuer.addItem('task');
queuer.addItem('task2', 'front');
queuer.addItem('task');
queuer.addItem('task2', 'front');

Parameters

item

TValue

position

QueuePosition = ...

runOnItemsChange

boolean = true

Returns

boolean


clear()

ts
clear(): void
clear(): void

Defined in: queuer.ts:620

Removes all pending items from the queue. Does not affect items being processed.

Returns

void


execute()

ts
execute(position?): undefined | TValue
execute(position?): undefined | TValue

Defined in: queuer.ts:485

Removes and returns the next item from the queue and processes it using the provided function.

Example usage:

ts
queuer.execute();
// LIFO
queuer.execute('back');
queuer.execute();
// LIFO
queuer.execute('back');

Parameters

position?

QueuePosition

Returns

undefined | TValue


flush()

ts
flush(numberOfItems, position?): void
flush(numberOfItems, position?): void

Defined in: queuer.ts:501

Processes a specified number of items to execute immediately with no wait time If no numberOfItems is provided, all items will be processed

Parameters

numberOfItems

number = ...

position?

QueuePosition

Returns

void


getNextItem()

ts
getNextItem(position): undefined | TValue
getNextItem(position): undefined | TValue

Defined in: queuer.ts:444

Removes and returns the next item from the queue without executing the function. Use for manual queue management. Normally, use execute() to process items.

Example usage:

ts
// FIFO
queuer.getNextItem();
// LIFO
queuer.getNextItem('back');
// FIFO
queuer.getNextItem();
// LIFO
queuer.getNextItem('back');

Parameters

position

QueuePosition = ...

Returns

undefined | TValue


peekAllItems()

ts
peekAllItems(): TValue[]
peekAllItems(): TValue[]

Defined in: queuer.ts:588

Returns a copy of all items in the queue.

Returns

TValue[]


peekNextItem()

ts
peekNextItem(position): undefined | TValue
peekNextItem(position): undefined | TValue

Defined in: queuer.ts:578

Returns the next item in the queue without removing it.

Example usage:

ts
queuer.peekNextItem(); // front
queuer.peekNextItem('back'); // back
queuer.peekNextItem(); // front
queuer.peekNextItem('back'); // back

Parameters

position

QueuePosition = 'front'

Returns

undefined | TValue


reset()

ts
reset(): void
reset(): void

Defined in: queuer.ts:628

Resets the queuer state to its default values

Returns

void


setOptions()

ts
setOptions(newOptions): void
setOptions(newOptions): void

Defined in: queuer.ts:281

Updates the queuer options. New options are merged with existing options.

Parameters

newOptions

Partial<QueuerOptions<TValue>>

Returns

void


start()

ts
start(): void
start(): void

Defined in: queuer.ts:595

Starts processing items in the queue. If already isRunning, does nothing.

Returns

void


stop()

ts
stop(): void
stop(): void

Defined in: queuer.ts:605

Stops processing items in the queue. Does not clear the queue.

Returns

void

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