shuffled-priority-queue

A priority queue that shuffles elements with the same priority.

npm install shuffled-priority-queue

Usage

const spq = require('shuffled-priority-queue')
const queue = spq()
 
queue.add({
  priority: 0,
  value: 'hello'
})
 
queue.add({
  priority: 0,
  value: 'world'
})
 
queue.add({
  priority: 1,
  value: 'welt'
})
 
queue.add({
  priority: 2,
  value: 'verden'
})
 
console.log(queue.shift()) // returns {value: 'verden'}
console.log(queue.shift()) // returns {value: 'welt'}
console.log(queue.shift()) // returns {value: 'hello'} or {value: 'world'}
console.log(queue.shift()) // returns {value: 'hello'} or {value: 'world'}
console.log(queue.shift()) // returns null (empty queue)

API

const queue = spq()

Create a new queue.

value = queue.add(value)

Add a new value to the queue. The value is returned for convenience If you set value.priority to a number, it'll be added to the queue at that priority.

queue.remove(value)

Remove a value from the queue.

bool = queue.has(value)

Check if a value is in the queue.

value = queue.shift()

Shift the next value off the queue.

The value returned will have the highest priority off the queue. If multiple values have the same priority a random one is returned.

value = queue.head()

Same as shift() but does not mutate the queue.

value = queue.pop()

Same as shift() but returns a value with the lowest priority.

value = queue.tail()

Same as pop() but does not mutate the queue.

queue.length

Property containing how many items are in the queue

for (const value of queue)

Iterate the queue from highest priority to lowest using the for of syntax

value = queue.next([prevValue])

Iterate the queue from highest priority to lowest.

let prevValue = null
 
while (prevValue = queue.next(prevValue)) {
  console.log('value:', prevValue)
}

value = queue.prev([prevValue])

Iterate the queue from lowest priority to highest.

let prevValue = null
 
while (prevValue = queue.prev(prevValue)) {
  console.log('value:', prevValue)
}

License

MIT