1次元配列をN個づつ区切り、2次元の配列を返す。

JavaScript 
function ArySplit (ary, n) {
  return (n < ary.length)
  ? Array.prototype.concat.apply ( [ary.splice (0, n)], [split (ary, n)] )
  : [ary]
}

カレンダーを作る
http://oshiete.goo.ne.jp/qa/7999208.html
WEB用カレンダーの不具合？について

質問者は、innerHTML を多用して、イベント処理まで書き込んでいる。ちと見づらい。
各月は、 caption から得る。一日の手前と末日の空白は、ちょっと小細工。
そして日付は、数字を３２進法にして文字に置き換え、それを区切って配列とし、7個づつ区切って
日付ノードに変換して書き込む。

<!DOCTYPE html>
<title></title>
<meta charset="UTF-8"/>
<style>
table.calendar {
  border-collapse: collapse;
  float: left;
  font-size : small;
  margin : 1em 2em;
  border : none;
  width :30em;
  height :18em;
}

table.calendar caption {
  text-align: left;
  padding: .5ex 1em;
  color : green;
  font-size: large;

}

table.calendar tr > * {
  color : #666;
  border : none;
  text-align : center;
  padding : .5ex;
}

table.calendar tr > *:nth-of-type(1) {
  color : #f22;
}
table.calendar tr > *:nth-of-type(7) {
  color : #22f;
}

table.calendar th {
  background : #eee;
  height : 1em;
}

table.calendar td {
  border-bottom : 1px #ddd solid;
}

</style>

<table class="calendar">
  <caption>2013-1</caption>
</table>

<table class="calendar" border="1">
  <caption>2013-2</caption>
</table>

<table class="calendar" border="1">
  <caption>2013-3</caption>
</table>

<table class="calendar" border="1">
  <caption>2013-4</caption>
</table>

<table class="calendar" border="1">
  <caption>2013-5</caption>
</table>

<table class="calendar" border="1">
  <caption>2013-6</caption>
</table>


<script>


(function () {
  var A = Array.prototype;
  var doc = document;
  var yyyymm_reg = /(\d{4}).*(\d{1,2})/;
  var num = '123456789abcdefghijklmnopqrstuv';
  var youbi = ['日','月', '火', '水', '木', '金', '土'];
 
  function Calendar () { ; }

  
  function insertTH (t) {
    var th = this.ownerDocument.createElement ('th');
    th.textContent = t;
    this.appendChild (th);
  }
  
  function insertTD (t) {
    this.insertCell (-1).textContent = t;
  }
  
  function insertTR (r) {
    r.forEach (insertTD, this.insertRow (-1));
  }
  
  function insertTRh (r) {
    r.forEach (insertTH, this.insertRow (-1));
  }
  
  function appendTbody (t, a) {
    a.forEach (insertTR, t);
  }

  
  function ArraySplit (ary, n) {
    return (n < ary.length)
      ? A.concat.apply ([ary.splice (0, n)], [ArraySplit (ary, n)]): [ary];
  }
  
  function makeDays (date) {
    var matubi = new Date (date.getFullYear (), date.getMonth () + 1, 0);
    var dayMax = matubi.getDate ();
    var week = matubi.getDay ();
    var begin = (7 + week - (dayMax % 7)) % 7 + 2;
    var map = [
          (new Array (begin)).join (' '),
          (num.substring (0, dayMax)),
          (new Array (7 - week)).join (' ')
       ].join('').split ('').map (function (c) { return ' ' === c ? c: parseInt (c, 32); });

    return ArraySplit (map, 7);
  }
  
  function dayFormat (date) {
    return [
      date.getFullYear (), '年',
      date.getMonth () + 1, '月'
    ].join (' ');
  }

 
  function theMonthObj (str) {
    var ym = yyyymm_reg.exec (str);
    return (ym) ? new Date (ym[1], ym[2]-1, 1): new Date;
  }

  
  function create (table) {
    var caption = table.querySelector ('caption');
    var tbody = doc.createElement ('tbody');
    var base = theMonthObj (caption ? caption.textContent: null);

    if (caption)
      caption.textContent = dayFormat (base);

    insertTRh.call (tbody, youbi);
    appendTbody (tbody, makeDays (base));
    table.appendChild (tbody);
   }
  
  Calendar.create = create;
  
  this.Calendar = Calendar;
}) ();



var table = document.querySelectorAll ('table.calendar');

Array.prototype.forEach.call (table, Calendar.create);
</script>