trying out PQ

pq.js

class QElement {
	constructor (value, priority) {
		this.value = value;
		this.priority = priority
	}
}

class PQ {
	constructor () {
		this.elements = ['root'];
	}

	enqueue(e) {
		this.elements.push(e);
		this.swim(this.elements.length - 1);
	}

	swim(index) {
		
		while(index > 1 && this.lower(Math.floor(index / 2), index)) {
			this.swap(Math.floor(index / 2), index);
			index = Math.floor(index / 2);
		}
	}

	lower(i1, i2) {
		return this.elements[i1].priority < this.elements[i2].priority;
	}

	swap(i1, i2) {
		let tmp = this.elements[i1];
		this.elements[i1] = this.elements[i2];
		this.elements[i2] = tmp;
	}

	sink(index) {
		let child = index * 2;
		while(child < this.elements.length) {
			// find bigger child
			if ((child + 1 < this.elements.length) && this.lower(child, child + 1)) {
				child++;
			}

			if (this.lower(index, child)) {
				this.swap(index, child);
				index = child;
			} else {
				break;
			}
		}
	}

	delMax() {
		this.swap(1, this.elements.length - 1);
		this.sink(1);

		return this.elements.pop();
	}

	isEmpty() {
		return this.elements.length == 1;
	}
}

let queue = new PQ();

queue.enqueue(new QElement('xx', 10));
queue.enqueue(new QElement('xx', 13));
queue.enqueue(new QElement('xx', 8));
queue.enqueue(new QElement('xx', 28));
queue.enqueue(new QElement('xx', 2));
queue.enqueue(new QElement('xx', 50));

console.log(queue);

queue.delMax();
console.log(queue);