//Queue
var Queue = require('spque').Queue
let q = new Queue

q.put(2)
q.put(4)

console.log(
    q.size, q.get()
)
//2 2

//Stack
var Stack = require('spque').Stack
let q = new Stack

q.put(2)
q.put(4)

console.log(
    q.size, q.get()
)
//2 4

//Priority Queue
var PQueue = require('spque').PQueue
let q = new PQueue

q.put(2)
q.put(4)

console.log(
    q.size, q.get()
)
//2 4

let mypq = new (require('spque').PQueue)()

mypq.comparator = (a, b) =>
    a.toUpperCase()
     .localeCompare(
         b.toUpperCase()
     )

mypq.put('I')
mypq.put('want')
mypq.put('to')
mypq.put('break')
mypq.put('free')

while (mypq.size)
    console.log(mypq.get())

Test:

var PQueue = require('spque').PQueue_min
let q = new PQueue
let most
for (i=0;i<100000;i++) q.put( Math.round( Math.random()*1000000000 ) )

console.log(q.size);

let elozo=1
while (q.size) {
    if ( elozo >= (most = q.get() ) ) console.log('equal or mistake',most,elozo);
    elozo=most
}