binary-heap.js

function BinaryHeap(scoreFunction) {
    this.content = [];
    this.scoreFunction = scoreFunction;
}

BinaryHeap.prototype = {
    push: function(element) {
        this.content.push(element);
        this.sinkDown(this.content.length - 1);
    },
    pop: function() {
        const result = this.content[0];
        const end = this.content.pop();
        if (this.content.length > 0) {
            this.content[0] = end;
            this.bubbleUp(0);
        }
        return result;
    },
    remove: function(node) {
        const i = this.content.indexOf(node);
        const end = this.content.pop();
        if (i !== this.content.length - 1) {
            this.content[i] = end;

            if (this.scoreFunction(end) < this.scoreFunction(node)) {
                this.sinkDown(i);
            } else {
                this.bubbleUp(i);
            }
        }
    },
    size: function() {
        return this.content.length;
    },
    rescoreElement: function(node) {
        this.sinkDown(this.content.indexOf(node));
    },
    sinkDown: function(n) {
        const element = this.content[n];
        while (n > 0) {

            const parentN = ((n + 1) >> 1) - 1;
            const parent = this.content[parentN];
            if (this.scoreFunction(element) < this.scoreFunction(parent)) {
                this.content[parentN] = element;
                this.content[n] = parent;
                n = parentN;
            } else {
                break;
            }
        }
    },
    bubbleUp: function(n) {
        const length = this.content.length;
        const element = this.content[n];
        const elemScore = this.scoreFunction(element);

        while (true) {
            const child2N = (n + 1) << 1;
            const child1N = child2N - 1;
            let swap = null;
            let child1Score;
            if (child1N < length) {
                const child1 = this.content[child1N];
                child1Score = this.scoreFunction(child1);
                if (child1Score < elemScore) {
                    swap = child1N;
                }
            }

            if (child2N < length) {
                const child2 = this.content[child2N];
                const child2Score = this.scoreFunction(child2);
                if (child2Score < (swap === null ? elemScore : child1Score)) {
                    swap = child2N;
                }
            }

            if (swap !== null) {
                this.content[n] = this.content[swap];
                this.content[swap] = element;
                n = swap;
            } else {
                break;
            }
        }
    }
};