JS中关于正则的巧妙操作

var msg="dsada[emoji:37]dsadas[emoji:3900]法拉芬河";function fetch(msg) {  var match, result = msg,    reg = //[emoji:/d+/]/g,    emojiIndex,    totalEmojiNum = 45;  while (match = reg.exec(msg)) {    console.log(match[0]);//[emoji:37],[emoji:3900]    emojiIndex = match[0].slice(7, -1);    console.log(emojiIndex);//37,3900    if (emojiIndex > totalEmojiNum) {      result = result.replace(match[0], '[X]');    } else {      result = result.replace(match[0], '<img src="images/eomji_' + emojiIndex + '.gif" />');    };  };  return result;//"dsada<img src="images/eomji_37.gif" />dsadas[X]法拉芬河"}fetch(msg);