半角から全角文字列へ

教えてgoo JavaScript 
var han= '1234567890abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ!"#$%&\'()=-~\\[]{}<>,.?/_';
var zen= '１２３４５６７８９０ａｂｃｄｅｆｇｈｉｊｋｌｍｎｏｐｑｒｓｔｕｖｗｘｙｚＡＢＣＤＥＦＧＨＩＪＫＬＭＮＯＰＱＲＳＴＵＶＷＸＹＺ！”＃＄％＆’（）＝−〜￥［］｛｝＜＞，．？／＿';

var toZenkaku =
  (function (rep) {
    return function () {
      return this.replace(/"/g,'”')
                 .replace(/'/g,"’")
                 .replace(/\\/g,'￥')
                 .replace(/[ -~]/g, rep); }; })
  (function (c) {
    return String.fromCharCode (c.charCodeAt (0) + 65248)})

String.prototype.toZenkaku = toZenkaku;

document.write([han, han.toZenkaku(), zen].join("<br>"));

replace 連発！　OTZ