Calculs avec javascript

Bonjour à tous,

Je travail sur un projet perso en code javascript.
Il s'agit d'un compteur de mots.
Je suis parti sur un code "opensource" et je n'arrive pas à apporter quelques modifications.
J'ai avoir la possibilité de choisir un multiplicateur au nombre de mots trouvés.
Par exemple : 156 (mots) et choisir avec une combobox X2, ou X3. Le résultat serait alors affiché dans une nouvelle zone : résultat ► xxxxx .
Et ensuite avec deux cases à cocher (l'une ajoute +1 et l'autre ajout +2)
ça parait simple à d'écrire, mais je galère grave... :-(

Merci pour votre aide,
Fichiers source : https://we.tl/t-1CZnWsi8wU

/*
 **
 ** User stories:
 ** - Shows number of characters, words, sentences, paragraphs - Done
 ** - Show reading time - Done
 ** - Show keyword count - Done
 ** - Show reading level (Optional - how?) - Done
 ** - Above data should change/appear on every keypress - Done
 **
 */

// Readability (Mashape) API Key for testing: PQ4FOFuaR6mshI6qpnQKQvkDZQXjp1o6Zcqjsnug7GvNggTzUE

"use strict";
var input = document.querySelectorAll('textarea')[0],
  characterCount = document.querySelector('#characterCount'),
  wordCount = document.querySelector('#wordCount'),
  sentenceCount = document.querySelector('#sentenceCount'),
  paragraphCount = document.querySelector('#paragraphCount'),
  readingTime = document.querySelector('#readingTime'),
  readability = document.querySelector('#readability'),
  keywordsDiv = document.querySelectorAll('.keywords')[0],
  topKeywords = document.querySelector('#topKeywords');

// updating the displayed stats after every keypress
input.addEventListener('keyup', function() {
  
  //keeping the console clean to make only the latest data visible
  console.clear();
  

  // character count
  // just displaying the input length as everything is a character
  characterCount.innerHTML = input.value.length;
  

  // word count using \w metacharacter - replacing this with .* to match anything between word boundaries since it was not taking 'a' as a word.
  // this is a masterstroke - to count words with any number of hyphens as one word
  // [-?(\w+)?]+ looks for hyphen and a word (we make both optional with ?). + at the end makes it a repeated pattern
  // \b is word boundary metacharacter
  var words = input.value.match(/\b[-?(\w+)?]+\b/gi);
  // console.log(words);
  if (words) {
    wordCount.innerHTML = words.length;
  } else {
    wordCount.innerHTML = 0;
  }


  // sentence count	using ./!/? as sentense separators
  if (words) {
    var sentences = input.value.split(/[.|!|?]+/g);
    console.log(sentences);
    sentenceCount.innerHTML = sentences.length - 1;
  } else {
    sentenceCount.innerHTML = 0;
  }


  // paragraph count from http://stackoverflow.com/a/3336537
  if (words) {
    // \n$ takes care of empty lines: lines with no characters, and only \n are not paragraphs
    // and need to be replaced with empty string
    var paragraphs = input.value.replace(/\n$/gm, '').split(/\n/);
    paragraphCount.innerHTML = paragraphs.length;
  } else {
    paragraphCount.innerHTML = 0;
  }
  // console.log(paragraphs);


  // reading time based on 150 words/minute
  if (words) {
    var seconds = Math.floor(words.length *  60 / 150);
    // need to convert seconds to minutes and hours
    if (seconds > 59) {
      var minutes = Math.floor(seconds / 60);
      seconds = seconds - minutes*60;
      readingTime.innerHTML = minutes + "m "+ seconds + "s";
    } else {
      readingTime.innerHTML = seconds + "s";
    }
  } else {
    readingTime.innerHTML = "0s";
  }


  // finding out top keywords and their count
  // step-1: remove all the stop words
  // step-2: form an object with keywords and their count
  // step-3: sort the object by first converting it to a 2D array
  // step-4: display top 4 keywords and their count
  
  if (words) {
    
    // step-1: removing all the stop words
    var nonStopWords = [];
    var stopWords = ["à","allô","aucuns","auriez","auxdits","aviez","ayons","bof","çà","certaines","chez","comment","da","desquels","deviez","devras","doit","dues","dût","es","êtes","eurêka","excepté","fouchtra","fûmes","ho","hurrah","laquelle","leur","mazette","mâtin","ne","nulle","or","outre","pas","plein","pourraient","pourvu","pouviez","puis","pussent","que","quoi","saperlipopette","serait","sien","sommes","ta","telles","touchant","une","veuillez","voilà","voudrez","voulante","voulue","vôtre afin","alors","auquel","aurions","auxquelles","avions","aïe","boum","car","certains","chic","concernant","dans","devaient","devions","devrez","doive","duquel","eh","et","étiez","eus","eûmes","furent","fût","holà","hé","le","leurs","me","miséricorde","ni","nulles","ôté","palsambleu","patatras","plouf","pourrais","pouvaient","pouvions","puisque","put","quel","quoique","sapristi","seras","sienne","son","tandis","tels","tous","unième","veuillons","vos","voudriez","voulantes","voulues","vôtres ah","apr.","aura","aurons","auxquels","avoir","bah","bravissimo","ce","ces","chiche","contre","de","devais","devoir","devriez","doivent","durant","elle","étaient","étions","eusse","eût","fus","fûtes","hop","il","ledit","lorsque","merci","moi","nonobstant","nuls","ou","pan","pechère","plus","pourrait","pouvais","pouvoir","puisse","pécaïre","quelle","rataplan","sauf","serez","siennes","sont","tant","tes","tout","unièmes","veulent","votre","voudrions","voulants","voulurent","zut ai","as","aurai","auront","avaient","avons","basta","bravo","ceci","cet","chouette","corbleu","debout","devait","devons","devrions","doives","durent","elles","étais","être","eussent","eûtes","fusse","grâce","hormis","ils","lequel","lui","merde","moins","nos","ô","où","par","pendant","plusieurs","pourras","pouvait","pouvons","puissent","pût","quelles","revoici","se","seriez","siens","sous","taratata","tien","toute","v'lan","veut","voudra","voudrons","voulez","voulus","aie","attendu","auraient","autant","avais","ayant","beaucoup","ç'a","cela","cette","chut","coucou","depuis","devant","devra","devrons","donc","dus","en","était","eu","eusses","évohé","fussent","ha","hors","jarnicoton","les","là","mes","mon","notre","oh","ouais","parbleu","peu","pouah","pourrez","pouvant","psitt","puisses","qq.","quelqu'un","revoilà","selon","serions","sinon","soyez","tayaut","tienne","toutes","va","veux","voudrai","voudront","vouliez","voulussent","aient","au","aurais","autre","avait","ayante","bernique","ç'aura","celle","ceux","ciao","couic","des","devante","devrai","devront","dont","dussent","encontre","étant","eue","eussiez","évoé","fusses","hein","hou","je","lesdites","ma","mien","morbleu","nôtre","ohé","ouf","parce","peuchère","pour","pourriez","pouvante","pst","puissiez","qqch.","quelqu'une","rien","sera","serons","soi","soyons","taïaut","tiennes","tu","vers","via","voudraient","voulaient","voulions","voulut","aies","aucun","aurait","autres","avant","ayantes","bien","ç'aurait","celles","chacun","clic","crac","desdites","devantes","devraient","dia","du","dut","endéans","étante","eues","eussions","fi","fussiez","hem","hourra","jusque","lesdits","made","mienne","motus","nôtres","olé","ouille","pardi","peut","pourquoi","pourrions","pouvantes","pu","puissions","qqn","quels","sa","serai","seront","soient","stop","te","tiens","tudieu","veuille","vivement","voudrais","voulais","vouloir","voulût","ait","aucune","auras","aux","avec","ayants","bigre","ç'avait","celui","chacune","clac","cric","desdits","devants","devrais","diantre","dudit","dès","entre","étantes","euh","eut","fichtre","fussions","hep","hue","la","lesquelles","mais","miennes","moyennant","nous","on","oust","pardieu","peuvent","pourra","pourrons","pouvants","pue","purent","quand","qui","sacristi","seraient","ses","sois","suis","tel","toi","turlututu","veuillent","vlan","voudrait","voulait","voulons","vous","al.","aucunes","aurez","auxdites","avez","ayez","bis","ça","cependant","chaque","comme","crénom","desquelles","devez","devrait","dois","due","dû","envers","étants","eurent","eux","fors","fut","heu","hum","ladite","lesquels","malgré","miens","na","nul","ont","ouste","parmi","peux","pourrai","pourront","pouvez","pues","pus","quant","quiconque","sans","serais","si","soit","sur","telle","ton","un","veuilles","voici","voudras","voulant","voulu","vu"];
    for (var i = 0; i < words.length; i++) {
      // filtering out stop words and numbers
      if (stopWords.indexOf(words[i].toLowerCase()) === -1 && isNaN(words[i])) {
        nonStopWords.push(words[i].toLowerCase());
      }
    }
    // console.log(nonStopWords);

    // step-2: forming an object with keywords and their count
    var keywords = {};
    for (var i = 0; i < nonStopWords.length; i++) {
      // checking if the word(property) already exists
      // if it does increment the count otherwise set it to one
      if(nonStopWords[i] in keywords) {
        keywords[nonStopWords[i]] += 1;
      } else {
        keywords[nonStopWords[i]] = 1;
      }
    }
    
    // step-3: sorting the object by first converting it to a 2D array
    var sortedKeywords = [];
    for (var keyword in keywords){
      sortedKeywords.push([keyword, keywords[keyword]])  
    }
    sortedKeywords.sort(function(a, b) {return b[1] - a[1]});
    // console.log(sortedKeywords);

    // step-4: displaying top 4 keywords and their count
    topKeywords.innerHTML = "";
    for (var i = 0; i < sortedKeywords.length && i < 4; i++) {
      var li = document.createElement('li');
      li.innerHTML = "<b>" + sortedKeywords[i][0] + "</b>: " + sortedKeywords[i][1];
      topKeywords.appendChild(li);
    }
  }

  // displaying top keywords only if there is a word in the text area
  if (words) {
    keywordsDiv.style.display = "block";
  } else {
    keywordsDiv.style.display = "none";
  }
  
});


// readability level using readability-metrics API from Mashape
readability.addEventListener('click', function() {
  
  // placeholder until the API returns the score  
  readability.innerHTML = "Fetching score...";

  var requestUrl = "https://ipeirotis-readability-metrics.p.mashape.com/getReadabilityMetrics?text=";
  var data = input.value;

  var request = new XMLHttpRequest();
  request.open('POST', encodeURI(requestUrl + data), true);
  request.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded; charset=UTF-8');
  request.setRequestHeader("X-Mashape-Authorization", "PQ4FOFuaR6mshI6qpnQKQvkDZQXjp1o6Zcqjsnug7GvNggTzUE");
  request.send();

  request.onload = function() {
    if (this.status >= 200 && this.status < 400) {
      // Success!
      readability.innerHTML = readingEase(JSON.parse(this.response).FLESCH_READING);
    } else {
      // We reached our target server, but it returned an error
      readability.innerHTML = "Not available.";
    }
  };

  request.onerror = function() {
    // There was a connection error of some sort
    readability.innerHTML = "Not available.";
  };
});

// function to convert FLESCH READING SCORE into meaningful string.
function readingEase(num) {
  switch(true) {
    case (num <= 30):
      return "Readability: College graduate.";
      break;
    case (num > 30 && num <= 50):
      return "Readability: College level.";
      break;
    case (num > 50 && num <= 60):
      return "Readability: Lycée.";
      break;
    case (num > 60 && num <= 70):
      return "Readability: 8th - 9th grade.";
      break;
    case (num > 70 && num <= 80):
      return "Readability: 7th grade.";
      break;
    case (num > 80 && num <= 90):
      return "Readability: 6th grade.";
      break;
    case (num > 90 && num <= 100):
      return "Readability: 5th grade.";
      break;
    default:
      return "Not available.";
      break;
  }
}