Function insertNode

docs/app/js/sanddance-app.js:102092–102104

(i, x, y, last)

    return b2;
}
function insertNode(i, x, y, last) {
    const p = new Node(i, x, y);
    if (!last) {
        p.prev = p;
        p.next = p;
    } else {
        p.next = last.next;
        p.prev = last;
        last.next.prev = p;
        last.next = p;
    }
    return p;
}
function removeNode(p) {
    p.next.prev = p.prev;
    p.prev.next = p.next;