updown - shows upvote/downvote counts for a reddit submission on click

updown

// ==UserScript==
// @name        updown
// @namespace   green_flash
// @description shows up/downvotes for submissions on click
// @include     *.reddit.com/r/*
// @version     1
// @grant       none
// ==/UserScript==

addButtons();

function addButtons()
{
    var linkListing = document.getElementsByClassName("linklisting")[0];
    var linkDivs = linkListing.getElementsByClassName("link");

    for(var i=0;i<linkDivs.length;i++)
    {
        var linkDiv = linkDivs[i];
        var buttonsList = linkDiv.getElementsByClassName("buttons")[0];
        var newButton = document.createElement("a");
        newButton.appendChild(document.createTextNode("show updowns"));
        newButton.setAttribute("linkIndex", i);
        newButton.href="javascript://void(0)";
        newButton.onclick = function() {handleClick(this);};
        var listElement = document.createElement("li");
        listElement.appendChild(newButton);
        listElement.onclick = function () {
            this.style.display='none';
        }
        buttonsList.appendChild(listElement);
    }
}


function handleClick(button)
{
    var linkIndex = button.getAttribute("linkIndex");

    var linkListing = document.getElementsByClassName("linklisting")[0];
    var linkDivs = linkListing.getElementsByClassName("link");    
    var linkDiv = linkDivs[linkIndex];
    
    var commentsLink = linkDiv.getElementsByClassName("comments")[0];
    var commentsPage = httpGet(commentsLink.href + "?limit=1&depth=1");
    var scoreSectionRegex = /<div class=(\"|\')score(\"|\')[\s\S]*?<\/div>/;
    var scoreSection = scoreSectionRegex.exec(commentsPage);
    
    var scoreRegex = /<span class=(\"|\')number(\"|\')>([\d\,\.]*?)<\/span>/;
    var score = scoreRegex.exec(scoreSection)[3].replace(',','').replace('.','');
    var upvotesPercentageRegex = /\((\d+)\s*\%[^\)]*\)/;
    var upvotesPercentage = upvotesPercentageRegex.exec(scoreSection)[1];
    var upvotes = calcUpvotes(score, upvotesPercentage);
    var downvotes = "--";
    if (upvotes != "--") {
        downvotes = upvotes - score;
    }
    
    var taglineParagraph = linkDiv.getElementsByClassName("tagline")[0];
    existingUpvoteSpans = taglineParagraph.getElementsByClassName("res_post_ups");
    existingDownvoteSpans = taglineParagraph.getElementsByClassName("res_post_downs");
    
    if (existingUpvoteSpans.length > 0 && existingDownvoteSpans.length > 0) {
        existingUpvoteSpans[0].textContent = "" + upvotes;
        existingDownvoteSpans[0].textContent = "" + downvotes;
        return;
    }
    
    var updownInfoSpan = document.createElement("span");
    
    var upvoteSpan = document.createElement("span");
    upvoteSpan.setAttribute("class", "res_post_ups");
    upvoteSpan.setAttribute("style", "color: #FF8B24;");
    upvoteSpan.appendChild(document.createTextNode(upvotes));

    var downvoteSpan = document.createElement("span");
    downvoteSpan.setAttribute("class", "res_post_downs");
    downvoteSpan.setAttribute("style", "color: #9494FF;");
    downvoteSpan.appendChild(document.createTextNode(downvotes));

    updownInfoSpan.appendChild(document.createTextNode("("));
    updownInfoSpan.appendChild(upvoteSpan);
    updownInfoSpan.appendChild(document.createTextNode("|"));
    updownInfoSpan.appendChild(downvoteSpan);
    updownInfoSpan.appendChild(document.createTextNode(") "));
    
    taglineParagraph.insertBefore(updownInfoSpan,taglineParagraph.firstChild);
}

function calcUpvotes(score, upvotesPercentage)
{
    var upvotes;
    if (score != 0) {
        upvotes = Math.round(((upvotesPercentage / 100) * score) / (2 * (upvotesPercentage / 100) - 1));
    } else {
        upvotes = "--";
    }
    return upvotes;
}

function httpGet(theUrl)
{
    var xmlHttp = null;

    xmlHttp = new XMLHttpRequest();
    xmlHttp.open( "GET", theUrl, false );
    xmlHttp.send( null );
    return xmlHttp.responseText;
}