TextStatistics.js

(function(glob) {
  function cleanText(text) {
    var fullStopTags = ["li", "p", "h1", "h2", "h3", "h4", "h5", "h6", "dd"];
    fullStopTags.forEach(function(tag) {
      text = text.replace("</" + tag + ">", ".");
    });
    text = text.replace(/<[^>]+>/g, "").replace(/[,:;()\-]/, " ").replace(/[\.!?]/, ".").replace(/^\s+/, "").replace(/[ ]*(\n|\r\n|\r)[ ]*/, " ").replace(/([\.])[\. ]+/, ".").replace(/[ ]*([\.])/, ". ").replace(/\s+/, " ").replace(/\s+$/, "");
    text += ".";
    return text;
  }
  var TextStatistics = function TextStatistics(text) {
    this.text = text ? cleanText(text) : this.text;
  };
  TextStatistics.prototype.fleschKincaidReadingEase = function(text) {
    text = text ? cleanText(text) : this.text;
    return Math.round((206.835 - 1.015 * this.averageWordsPerSentence(text) - 84.6 * this.averageSyllablesPerWord(text)) * 10) / 10;
  };
  TextStatistics.prototype.fleschKincaidGradeLevel = function(text) {
    text = text ? cleanText(text) : this.text;
    return Math.round((.39 * this.averageWordsPerSentence(text) + 11.8 * this.averageSyllablesPerWord(text) - 15.59) * 10) / 10;
  };
  TextStatistics.prototype.gunningFogScore = function(text) {
    text = text ? cleanText(text) : this.text;
    return Math.round((this.averageWordsPerSentence(text) + this.percentageWordsWithThreeSyllables(text, false)) * .4 * 10) / 10;
  };
  TextStatistics.prototype.colemanLiauIndex = function(text) {
    text = text ? cleanText(text) : this.text;
    return Math.round((5.89 * (this.letterCount(text) / this.wordCount(text)) - .3 * (this.sentenceCount(text) / this.wordCount(text)) - 15.8) * 10) / 10;
  };
  TextStatistics.prototype.smogIndex = function(text) {
    text = text ? cleanText(text) : this.text;
    return Math.round(1.043 * Math.sqrt(this.wordsWithThreeSyllables(text) * (30 / this.sentenceCount(text)) + 3.1291) * 10) / 10;
  };
  TextStatistics.prototype.automatedReadabilityIndex = function(text) {
    text = text ? cleanText(text) : this.text;
    return Math.round((4.71 * (this.letterCount(text) / this.wordCount(text)) + .5 * (this.wordCount(text) / this.sentenceCount(text)) - 21.43) * 10) / 10;
  };
  TextStatistics.prototype.textLength = function(text) {
    text = text ? cleanText(text) : this.text;
    return text.length;
  };
  TextStatistics.prototype.letterCount = function(text) {
    text = text ? cleanText(text) : this.text;
    text = text.replace(/[^a-z]+/ig, "");
    return text.length;
  };
  TextStatistics.prototype.sentenceCount = function(text) {
    text = text ? cleanText(text) : this.text;
    return text.replace(/[^\.!?]/g, "").length || 1;
  };
  TextStatistics.prototype.wordCount = function(text) {
    text = text ? cleanText(text) : this.text;
    return text.split(/[^a-z0-9]+/i).length || 1;
  };
  TextStatistics.prototype.averageWordsPerSentence = function(text) {
    text = text ? cleanText(text) : this.text;
    return this.wordCount(text) / this.sentenceCount(text);
  };
  TextStatistics.prototype.averageSyllablesPerWord = function(text) {
    text = text ? cleanText(text) : this.text;
    var syllableCount = 0, wordCount = this.wordCount(text), self = this;
    text.split(/\s+/).forEach(function(word) {
      syllableCount += self.syllableCount(word);
    });
    return (syllableCount || 1) / (wordCount || 1);
  };
  TextStatistics.prototype.wordsWithThreeSyllables = function(text, countProperNouns) {
    text = text ? cleanText(text) : this.text;
    var longWordCount = 0, self = this;
    countProperNouns = countProperNouns === false ? false : true;
    text.split(/\s+/).forEach(function(word) {
      if (!word.match(/^[A-Z]/) || countProperNouns) {
        if (self.syllableCount(word) > 2) {
          longWordCount++;
        }
      }
    });
    return longWordCount;
  };
  TextStatistics.prototype.percentageWordsWithThreeSyllables = function(text, countProperNouns) {
    text = text ? cleanText(text) : this.text;
    return this.wordsWithThreeSyllables(text, countProperNouns) / this.wordCount(text) * 100;
  };
  TextStatistics.prototype.syllableCount = function(word) {
    var syllableCount = 0, prefixSuffixCount = 0, wordPartCount = 0;
    word = word.toLowerCase().replace(/[^a-z]/g, "");
    var problemWords = {"simile":3, "forever":3, "shoreline":2};
    if (problemWords.hasOwnProperty(word)) {
      return problemWords[word];
    }
    var subSyllables = [/cial/, /tia/, /cius/, /cious/, /giu/, /ion/, /iou/, /sia$/, /[^aeiuoyt]{2,}ed$/, /.ely$/, /[cg]h?e[rsd]?$/, /rved?$/, /[aeiouy][dt]es?$/, /[aeiouy][^aeiouydt]e[rsd]?$/, /^[dr]e[aeiou][^aeiou]+$/, /[aeiouy]rse$/];
    var addSyllables = [/ia/, /riet/, /dien/, /iu/, /io/, /ii/, /[aeiouym]bl$/, /[aeiou]{3}/, /^mc/, /ism$/, /([^aeiouy])\1l$/, /[^l]lien/, /^coa[dglx]./, /[^gq]ua[^auieo]/, /dnt$/, /uity$/, /ie(r|st)$/];
    var prefixSuffix = [/^un/, /^fore/, /ly$/, /less$/, /ful$/, /ers?$/, /ings?$/];
    prefixSuffix.forEach(function(regex) {
      if (word.match(regex)) {
        word = word.replace(regex, "");
        prefixSuffixCount++;
      }
    });
    wordPartCount = word.split(/[^aeiouy]+/ig).filter(function(wordPart) {
      return !!wordPart.replace(/\s+/ig, "").length;
    }).length;
    syllableCount = wordPartCount + prefixSuffixCount;
    subSyllables.forEach(function(syllable) {
      if (word.match(syllable)) {
        syllableCount--;
      }
    });
    addSyllables.forEach(function(syllable) {
      if (word.match(syllable)) {
        syllableCount++;
      }
    });
    return syllableCount || 1;
  };
  function textStatistics(text) {
    return new TextStatistics(text);
  }
  typeof module != "undefined" && module.exports ? module.exports = textStatistics : typeof define != "undefined" ? define("textstatistics", [], function() {
    return textStatistics;
  }) : glob.textstatistics = textStatistics;
})(this);