Reddit Comment Highlighter

Reddit_Comment_Highlighter.user.js

// ==UserScript==
// @name        Reddit Comment Highlighter
// @namespace   https://gist.github.com/fgrsnau
// @include     http://www.reddit.com/r/*/comments/*
// @include     https://www.reddit.com/r/*/comments/*
// @version     1
// @grant       none
// ==/UserScript==

var id = $('.content .sitetable .thing:first').attr('data-fullname');
var cookie = 'lastvisit_' + id;
var btnReset = $('<a href="#" class="title-button"></a>');
var btnAdjust = $('<a href="#" class="title-button">(adjust last visit)</a>');
var dateOfLoad = new Date();
$('.panestack-title').append(btnReset, btnAdjust);

function highlight(date) {
  console.log('Highlighting comments newer than ' + date + '.');

  var filterFunc = function() {
    str = $('.live-timestamp', this).attr('datetime');
    d = new Date(str);
    return d > date;
  };

  var entries = $('.commentarea .entry');
  entries.not(filterFunc).removeClass('new-comment');
  entries = entries.filter(filterFunc);
  entries.addClass('new-comment');
  btnReset.text(entries.length + ' new comments!');
}

function load() {
  var lastVisit = parseInt(localStorage.getItem(cookie));
  if (isNaN(lastVisit)) {
    lastVisit = 0;
  }
  return new Date(lastVisit);
}

function store(date) {
  localStorage.setItem(cookie, date.valueOf());
}

btnReset.on('click', function(event) {
  event.preventDefault();
  store(dateOfLoad);
  highlight(dateOfLoad);
});

btnAdjust.on('click', function(event) {
  event.preventDefault();
  var str = prompt('Last visit was [xx] hours ago?', '1');
  var h = parseInt(str);
  if (! isNaN(h)) {
    var d = new Date(dateOfLoad - h * 60 * 60 * 1000);
    store(d);
    highlight(d);
  }
});

highlight(load());