A javascript implementation of a priority queue. The queue is backed by a binary heap and provides O(lg n) insert/remove operations and O(1) retrieval of the highest priority item. Depending on if a MaxPriorityQueue or a MinPriorityQueue is initialized, the highest priority item can be the maximum or minimum.

• Installation
• Usage
• API

npm i vanilla-priority-queue --save

const {  MinPriorityQueue, MaxPriorityQueue } = require('vanilla-priority-queue');

let minPriorityQueue = new MinPriorityQueue();
/*
    The insert operation takes an item and it's priority.
    The item argument can be anything.
    The priority argument must be provided as an integer value.
*/
minPriorityQueue.insert(3, 3);
minPriorityQueue.insert(10, 10);
minPriorityQueue.peek() // returns 3
minPriorityQueue.remove() // returns 3
minPriorityQueue.remove() // returns 10
minPriorityQueue.isEmpty() // returns true


let maxPriorityQueue = new MaxPriorityQueue();
maxPriorityQueue.insert(3, 3);
maxPriorityQueue.insert(10, 10);
maxPriorityQueue.peek() // returns 10
maxPriorityQueue.remove() // returns 10
maxPriorityQueue.remove() // returns 3
maxPriorityQueue.isEmpty() // returns true

Both the MaxPriorityQueue and MinPriorityQueue expose the following functions:

• peek()

Returns the highest priority item in the queue in constant O(1) time. For a MaxPriorityQueue this is the max item. For a MinPriorityQueue this is the min item.

• insert(item, priority)

The insert operation takes an item and it's priority and inserts the following object into the queue:

{
    item: item, 
    priority: priority
} 

The item argument can be anything. The priority argument must be provided as an integer.

The operation completes in O(lg n) time.

• remove()

Removes the highest priority item in the queue in O(lg n) time. For a MaxPriorityQueue this is the max item. For a MinPriorityQueue this is the min item.

• isEmpty()

Returns a boolean value indicating whether the queue is empty or not.

• length()

Returns the length of the queue.

• getHeap()

Returns an array representation of the binary heap backing the priority queue. Note that this contains a dummy null element at index 0.