onchain-pulsar/src/consumer/priorityQueue/index.js

A package that natively supports pulsar api

class PriorityQueue {
  constructor({ maxQueueSize, logger }) {
    this.items = [];
    this.maxQueueSize = maxQueueSize;
    this.logger = logger;
  }

  enqueue(element, priority) {
    if (this.items.length === this.maxQueueSize + 1)
      this.logger.warn(
        `The queue has reached the maximum size, still adding to queue but may cause issues.`
      );
    const qElement = { element, priority };
    let contain = false;
    // for, for performance
    for (let i = 0; i < this.items.length; i++) {
      if (this.items[i].priority > qElement.priority) {
        this.items.splice(i, 0, qElement);
        contain = true;
        break;
      }
    }
    if (!contain) {
      this.items.push(qElement);
    }
  }

  dequeue() {
    if (this.isEmpty()) return 'Underflow';
    return this.items.shift().element;
  }

  front() {
    if (this.isEmpty()) return 'No elements in Queue';
    return this.items[0];
  }

  rear() {
    if (this.isEmpty()) return 'No elements in Queue';
    return this.items[this.items.length - 1];
  }

  isEmpty() {
    return this.items.length === 0;
  }

  length() {
    return this.items.length;
  }
}

module.exports = PriorityQueue;