hacker-news.js

// ==UserScript==
// @name        yc
// @namespace   yc
// @include     https://news.ycombinator.com/*
// @version     0.1
// @grant       GM_addStyle
// ==/UserScript==

GM_addStyle("                         \
  .ind {                              \
    border-right: 1px dotted #cccccc; \
    position: relative;               \
}                                     \
.ind::before {                        \
    color: #cccccc;                   \
    content: '^';                     \
    font-size: 10px;                  \
    position: absolute;               \
    right: -4px;                      \
    top: -3px;                        \
}                                     \
.subtext a.high {background: #f38a8ae6;color: #fff;} \
.subtext a.medium {background: #ec8e34e6;color: #fff;} \
");

(function() {
  if (window.location == "https://news.ycombinator.com/news"){
    computeAvgCommentNr();
  }
  
  function computeAvgCommentNr(){
    var commentsArray = [];
    var comments = [];
    var commentsNumbers = [];
    commentsArray = document.querySelectorAll('td.subtext a:nth-of-type(3n)');

    for(var i=0; i<commentsArray.length; i++){
      comments.push({"comments":commentsArray[i].textContent.replace("comments", "").slice(0,-1), "id": i});
    }

    for(var i=0; i<commentsArray.length; i++){
     commentsNumbers.push(commentsArray[i].textContent.replace("comments", "").slice(0,-1));
    }
    console.log(avg(commentsNumbers));
  }
  
  
  /*
  *
  * helper functions
  *
  */
  
  /*
  return average from an Array of numbers
  */
  function avg(elmt){
    var sum = 0;
    for(var i = 0; i < elmt.length; i++){
      sum += parseInt( elmt[i], 10 );
    }
    return Math.round(sum/elmt.length);
  }
})();