HN Most Replied Comments

index.js

// Shows only the most replied comments in https://news.ycombinator.com post and
// comment pages.

(() => {
  const INDENT_WIDTH = 12; // TODO Detect it automatically?

  class CommentTreeNode {
    constructor(attrs) {
      this.children = [];
      Object.assign(this, attrs);
    }

    nest(node) {
      this.children.push(node);
      node.parent = this;
    }

    visit(callback) {
      callback(this);
      this.children.forEach(child => child.visit(callback));      
    }

    // All nodes are comments but the root
    get isComment() {
      return this.domNode;
    }

    get domNodeIndent() {
      return this.domNode && this.domNode.querySelector('.ind img').width / INDENT_WIDTH;
    }
  }

  const getCommentsTree = () => {
    const tree = new CommentTreeNode;
    let reference = tree;
    document.querySelectorAll('.comtr').forEach(domNode => {
      const node = new CommentTreeNode({ domNode });
      while (node.domNodeIndent <= reference.domNodeIndent) reference = reference.parent;
      reference.nest(node);
      reference = node;
    });
    return tree;
  };

  const getComments = () => {
    const comments = [];
    getCommentsTree().visit(node => node.isComment && comments.push(node));
    return comments;
  }

  const showOnlyMostRepliedComments = ({ max }) => {
    getComments()
      .sort((comment1, comment2) => comment2.children.length - comment1.children.length)
      .forEach((comment, i) => {
        const show = i <= max - 1;
        comment.domNode.querySelector('.comment').style.display = show ? 'block' : 'none';        
      });
  };

  showOnlyMostRepliedComments({ max: 8 });
})();