questionID = 45040

commentsURL = 'https://api.stackexchange.com/2.2/questions/' + questionID + '/comments?order=asc&sort=creation&site=codegolf&filter=!t)IWLXOkOvAuPe8m2xJrXOknWcw(ZqZ'

answersURL = 'https://api.stackexchange.com/2.2/questions/' + questionID + '/answers?order=desc&sort=activity&site=codegolf&filter=!.FjsvG2LuND(frE*)WTvqQev1.lyu'

commentPattern = /^#### (\d+) -> (\\(?:n|s)|[ -~]) ####$/
answerPattern = /<pre><code>((?:\n|.)*?)\n<\/code><\/pre>/

chars = '\n !"#$%&\'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~'

validAnswers = []
invalidAnswers = []
invalidComments = []

userIDs = {}
usedWeights = {}
usedChars = {}
weights = {}
defaultWeight = chars.length + 1

for (var i = 0; i < chars.length; i++) {
    usedChars[chars[i]] = false
    usedWeights[i + 1] = false
    weights[chars[i]] = defaultWeight
}

function compute() {
    var score = computeScore($('#code').val())    
    $('#score').val(score == -1 ? 'Invalid characters' : score)
}

function computeScore(code) {
    var score = 0
    for(var i = 0; i < code.length; i++) {
        if (weights.hasOwnProperty(code[i])) {
            score += weights[code[i]]   
        } else {
            return -1
        }
    }
    return score
}

function htmlDecode(input)  {
  var e = document.createElement('div')
  e.innerHTML = input;
  return e.childNodes.length === 0 ? '' : e.childNodes[0].nodeValue
}

function addLeaderboard() {
    validAnswers.sort(function(a,b) { return a.score > b.score} )
    
    var place = 1
    var rows = ''
    
    for(var i = 0; i < validAnswers.length; i++) {
       var a = validAnswers[i]
       rows +=
           '<tr><td>' + place +
           "</td><td><a href='" + a.link + "'>" + a.owner.display_name + "</a></td><td>" +
           a.score + '</td><td>' + a.length + '</td></tr>'
       
       if (i + 1 < validAnswers.length && validAnswers[i + 1].score > a.score) {
           place++   
       }
    }
    
    $('#leaderboard').append(rows)   
}

function addAnalytics() {
    //assigned weights
    var assigned = ''
    for (var key in weights) {
        if (weights.hasOwnProperty(key) && weights[key] != defaultWeight) {
            assigned += (key == '\n' ? '\\n' : key) + '=' + weights[key] + ' '
        }
    }
    $('#weights').val(assigned)
    
    //unused chars
    var unusedc = ''
    for (var key in usedChars) {
        if (usedChars.hasOwnProperty(key) && usedChars[key] == false) {
            unusedc += key == '\n' ? '\\n' : key
        }
    }
    $('#unusedc').val(unusedc)
    
    //unused weights
    var unusedw = ''
    for (var key in usedWeights) {
        if (usedWeights.hasOwnProperty(key) && usedWeights[key] == false) {
            unusedw += key + ' '
        }
    }
    $('#unusedw').val(unusedw)
    
    //invalid comments
    var invalidc = ''
    if (invalidComments.length > 0) {
        for (var i = 0; i < invalidComments.length; i++) {
            var c = invalidComments[i]
            invalidc += "<a href='#" + c.link + "'>" + c.owner.display_name + '</a> '
        }
    } else {
        invalidc = 'none'
    }
    $('#comments').html(invalidc)
    
    //invalid answers
    var invalida = ''
    if (invalidAnswers.length > 0) {
        for (var i = 0; i < invalidAnswers.length; i++) {
            var a = invalidAnswers[i]
            invalida += "<a href='#" + a.link + "'>" + a.owner.display_name + '</a> '
        }
    } else {
        invalida = 'none'   
    }
    $('#answers').html(invalida)
}

function checkAnswers(answers) {
    for (var i = 0; i < answers.items.length; i++) {
        var answer = answers.items[i]
        var match = answerPattern.exec(answer.body)
        if (match) {
            var code = htmlDecode(match[1])
            var score = computeScore(code)
            if (score == -1) {
                invalidAnswers.push(answer)
            } else {
                answer.length = code.length
                answer.score = score
                validAnswers.push(answer)
            }
        } else {
            invalidAnswers.push(answer)
        }
    }
    
    addLeaderboard()
    addAnalytics()
}

function checkComments(comments) {
    for (var i = 0; i < comments.items.length; i++) {
        var comment = comments.items[i]
        var match = commentPattern.exec(htmlDecode(comment.body))
        if (match) {
            var userID = comment.owner.user_id            
            var weight = parseInt(match[1])
            var char = match[2] == '\\n' ? '\n' : (match[2] == '\\s' ? ' ' : match[2])

            //check validity
            if (userIDs.hasOwnProperty(userID) ||
                !usedWeights.hasOwnProperty(weight) || usedWeights[weight] ||
                !usedChars.hasOwnProperty(char) || usedChars[char])
            {
                invalidComments.push(comment)
            } else {
                userIDs[userID] = true
                usedWeights[weight] = true
                usedChars[char] = true
                weights[char] = weight
            }
        }
    }
    $.get(answersURL, checkAnswers)
}

function refresh() {
    $.get(commentsURL, checkComments)
}

refresh()

* {
    font-family: Helvetica, Arial, sans-serif;
}

table {
    border: 3px solid green;
    border-collapse: collapse;
}

button {
    font-size: 100%;
}

th {
    background-color: green;
    color: white;
    padding: 6pt;
}
    
td {
    border: 1px solid green;
    padding: 6pt;
}

.large{
    font-size: 140%;
}

.title{
    font-weight: bold;
    margin: 6pt 0 6pt 0;
}

textarea {
    font-family: "Courier New";
    white-space: nowrap; overflow: auto;
}

input[readonly]
{
    background-color: gainsboro;
}

.analytics {
    font-size: 90%;
    padding: 4pt 0 0 0;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class='large title'>Leaderboard</div>
<table id='leaderboard'>
  <tr>
    <th>Place</th>
    <th>Submitter</th>
      <th>Score</th>
    <th>Program Length</th>
  </tr>
</table>
<br>
<div class='title'>Compute Score</div>
<textarea id='code' rows='5' cols ='40' placeholder='paste code here...'></textarea><br>
<button type='button' onclick='compute()'>Compute</button> Score: <input type='text' id='score' readonly>
<br>
<br>
<div class='title'>Analytics</div>
<div class='analytics'>Assigned weights: <input type='text' id='weights' readonly></div>
<div class='analytics'>Unused characters: <input type='text' id='unusedc' readonly> (all weight 97)</div>
<div class='analytics'>Unused weights: <input type='text' id='unusedw' readonly></div>
<div class='analytics'>Invalid comments (duplicate user/char/weight):&nbsp;<span id='comments'></span></div>
<div class='analytics'>Invalid answers (illegal characters or no code block):&nbsp;<span id='answers'><span></div>
<br>
<button type='button' onclick='refresh'>Refresh</button>