# What is the most frequent word?

Given a text file, your program much trawl through it, counting the frequencies of each word, then output the most used word. Because a text file has no fixed length, and so can get very long, your code must be as short as possible.

## Rules/Requirements

 - Each submission should be either a full program or function. If it is a function, it must be runnable by only needing to add the function call to the bottom of the program. Anything else (e.g. headers in C), must be included.
 - There must be a free interpreter/compiler available for your language.
 - If it is possible, provide a link to a site where your program can be tested.
 - Your program must not write anything to `STDERR`.
 - Your program should take input from a text file or `STDIN` (or the closest alternative in your language).
 - [Standard loopholes](http://meta.codegolf.stackexchange.com/questions/1061/loopholes-that-are-forbidden-by-default) are forbidden.
 - Your program must be case-insensitive (`tHe`, `The` and `the` all contribute to the count of `the`).
 - If there is no most frequent word (see test case #3), your program should output nothing.

## Test Cases

    The man walked down the road.
    ==> the
    
    -----
    
    Slowly, he ate the pie, savoring each delicious bite. He felt like he was truly happy.
    ==> he
    
    -----
    
    This sentence has no most frequent word.
    ==> 
(The last test case has no output)

## Scoring

Programs are scored according to bytes. The usual character set is UTF-8, if you are using another please specify.

When the challenge finishes, the program with the least bytes (it's called [tag:code-golf]), will win.

## Submissions

To make sure that your answer shows up, please start your answer with a headline, using the following Markdown template:

    # Language Name, N bytes

where `N` is the size of your submission. If you improve your score, you *can* keep old scores in the headline, by striking them through. For instance:

    # Ruby, <s>104</s> <s>101</s> 96 bytes

If there you want to include multiple numbers in your header (e.g. because your score is the sum of two files or you want to list interpreter flag penalties separately), make sure that the actual score is the *last* number in the header:

    # Perl, 43 + 2 (-p flag) = 45 bytes

You can also make the language name a link which will then show up in the leaderboard snippet:

    # [><>](http://esolangs.org/wiki/Fish), 121 bytes

## Leaderboard

Here is a Stack Snippet to generate both a regular leaderboard and an overview of winners by language.

<!-- begin snippet: js hide: true -->

<!-- language: lang-js -->

    /* Configuration */

    var QUESTION_ID = 79576; // Obtain this from the url
    // It will be like https://XYZ.stackexchange.com/questions/QUESTION_ID/... on any question page
    var ANSWER_FILTER = "!t)IWYnsLAZle2tQ3KqrVveCRJfxcRLe";
    var COMMENT_FILTER = "!)Q2B_A2kjfAiU78X(md6BoYk";
    var OVERRIDE_USER = 53406; // This should be the user ID of the challenge author.

    /* App */

    var answers = [], answers_hash, answer_ids, answer_page = 1, more_answers = true, comment_page;

    function answersUrl(index) {
      return "https://api.stackexchange.com/2.2/questions/" +  QUESTION_ID + "/answers?page=" + index + "&pagesize=100&order=desc&sort=creation&site=codegolf&filter=" + ANSWER_FILTER;
    }

    function commentUrl(index, answers) {
      return "https://api.stackexchange.com/2.2/answers/" + answers.join(';') + "/comments?page=" + index + "&pagesize=100&order=desc&sort=creation&site=codegolf&filter=" + COMMENT_FILTER;
    }

    function getAnswers() {
      jQuery.ajax({
        url: answersUrl(answer_page++),
        method: "get",
        dataType: "jsonp",
        crossDomain: true,
        success: function (data) {
          answers.push.apply(answers, data.items);
          answers_hash = [];
          answer_ids = [];
          data.items.forEach(function(a) {
            a.comments = [];
            var id = +a.share_link.match(/\d+/);
            answer_ids.push(id);
            answers_hash[id] = a;
          });
          if (!data.has_more) more_answers = false;
          comment_page = 1;
          getComments();
        }
      });
    }

    function getComments() {
      jQuery.ajax({
        url: commentUrl(comment_page++, answer_ids),
        method: "get",
        dataType: "jsonp",
        crossDomain: true,
        success: function (data) {
          data.items.forEach(function(c) {
            if (c.owner.user_id === OVERRIDE_USER)
              answers_hash[c.post_id].comments.push(c);
          });
          if (data.has_more) getComments();
          else if (more_answers) getAnswers();
          else process();
        }
      });  
    }

    getAnswers();

    var SCORE_REG = /<h\d>\s*([^\n,]*[^\s,]),.*?(\d+)(?=[^\n\d<>]*(?:<(?:s>[^\n<>]*<\/s>|[^\n<>]+>)[^\n\d<>]*)*<\/h\d>)/;

    var OVERRIDE_REG = /^Override\s*header:\s*/i;

    function getAuthorName(a) {
      return a.owner.display_name;
    }

    function process() {
      var valid = [];
      
      answers.forEach(function(a) {
        var body = a.body;
        a.comments.forEach(function(c) {
          if(OVERRIDE_REG.test(c.body))
            body = '<h1>' + c.body.replace(OVERRIDE_REG, '') + '</h1>';
        });
        
        var match = body.match(SCORE_REG);
        if (match)
          valid.push({
            user: getAuthorName(a),
            size: +match[2],
            language: match[1],
            link: a.share_link,
          });
        
      });
      
      valid.sort(function (a, b) {
        var aB = a.size,
            bB = b.size;
        return aB - bB
      });

      var languages = {};
      var place = 1;
      var lastSize = null;
      var lastPlace = 1;
      valid.forEach(function (a) {
        if (a.size != lastSize)
          lastPlace = place;
        lastSize = a.size;
        ++place;
        
        var answer = jQuery("#answer-template").html();
        answer = answer.replace("{{PLACE}}", lastPlace + ".")
                       .replace("{{NAME}}", a.user)
                       .replace("{{LANGUAGE}}", a.language)
                       .replace("{{SIZE}}", a.size)
                       .replace("{{LINK}}", a.link);
        answer = jQuery(answer);
        jQuery("#answers").append(answer);

        var lang = a.language;
        if (/<a/.test(lang)) lang = jQuery(lang).text();
        
        languages[lang] = languages[lang] || {lang: a.language, user: a.user, size: a.size, link: a.link};
      });

      var langs = [];
      for (var lang in languages)
        if (languages.hasOwnProperty(lang))
          langs.push(languages[lang]);

      langs.sort(function (a, b) {
        if (a.lang > b.lang) return 1;
        if (a.lang < b.lang) return -1;
        return 0;
      });

      for (var i = 0; i < langs.length; ++i)
      {
        var language = jQuery("#language-template").html();
        var lang = langs[i];
        language = language.replace("{{LANGUAGE}}", lang.lang)
                           .replace("{{NAME}}", lang.user)
                           .replace("{{SIZE}}", lang.size)
                           .replace("{{LINK}}", lang.link);
        language = jQuery(language);
        jQuery("#languages").append(language);
      }

    }

<!-- language: lang-css -->

    body { text-align: left !important}

    #answer-list {
      padding: 10px;
      width: 290px;
      float: left;
    }

    #language-list {
      padding: 10px;
      width: 290px;
      float: left;
    }

    table thead {
      font-weight: bold;
    }

    table td {
      padding: 5px;
    }

<!-- language: lang-html -->

    <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
    <link rel="stylesheet" type="text/css" href="//cdn.sstatic.net/codegolf/all.css?v=83c949450c8b">
    <div id="answer-list">
      <h2>Leaderboard</h2>
      <table class="answer-list">
        <thead>
          <tr><td></td><td>Author</td><td>Language</td><td>Size</td></tr>
        </thead>
        <tbody id="answers">

        </tbody>
      </table>
    </div>
    <div id="language-list">
      <h2>Winners by Language</h2>
      <table class="language-list">
        <thead>
          <tr><td>Language</td><td>User</td><td>Score</td></tr>
        </thead>
        <tbody id="languages">

        </tbody>
      </table>
    </div>
    <table style="display: none">
      <tbody id="answer-template">
        <tr><td>{{PLACE}}</td><td>{{NAME}}</td><td>{{LANGUAGE}}</td><td>{{SIZE}}</td><td><a href="{{LINK}}">Link</a></td></tr>
      </tbody>
    </table>
    <table style="display: none">
      <tbody id="language-template">
        <tr><td>{{LANGUAGE}}</td><td>{{NAME}}</td><td>{{SIZE}}</td><td><a href="{{LINK}}">Link</a></td></tr>
      </tbody>
    </table>

<!-- end snippet -->