JS鼠标行变颜色只能列A~Z,超过的部份无法着色

{
var background_color = "rgb(0,204,204)"; //新背景色
var frozen_back_color = new Array();
var back_color = new Array();
var ignor_list = "[id^=B]"; //指定某些列不高亮,形如[id^=A],[id^=B],逗号分割
var $last_tr;
var i = 0;
var nHead = 3;
$(".x-table tr[id]:gt(" + nHead + ")").bind("mouseenter", function() {
      if(typeof($last_tr) != "undefined") {
         if(typeof($(this).attr("id")) != "undefined") {
            if(typeof($("#content-container #frozen-west").attr("id")) != "undefined") {
                  $("#content-container #" + $last_tr.attr("id")).each(function() {
                     $(this).children("td").each(function() {
                        $(this).css("background-color", frozen_back_color[$(this).index()]);
                     });
                     i = i + 1;
                  });
                  i = 0;
            } else {
                  $last_tr.children("td").each(function() {
                     $(this).css("background-color", back_color[$(this).index()]);
                  });
            }
            frozen_back_color = [];
            back_color = [];
         }
      }
      if(typeof($(this).attr("id")) != "undefined") {
         if(typeof($("#content-container #frozen-west").attr("id")) != "undefined") {
            $("#content-container #" + $(this).attr("id")).each(function() {
                  frozen_back_color = new Array();
                  $(this).children("td").not(ignor_list).each(function() {
                     frozen_back_color[$(this).index()] = $(this).css("background-color");
                     if(typeof($(this).attr("rowspan")) == "undefined") {
                        $(this).css("background-color", background_color);
                     }
                  });
                  i = i + 1;
            });
            i = 0;
         } else {
            $(this).children("td").not(ignor_list).each(function() {
                  back_color[$(this).index()] = $(this).css("background-color");
                  if(typeof($(this).attr("rowspan")) == "undefined") {
                     $(this).css("background-color", background_color);
                  }
            });
         }
      }
});
$(".x-table tr[id]:gt(" + nHead + ")").bind("mouseleave", function() {
      if(typeof($(this).attr("id")) != "undefined") {
         $last_tr = $(this);
      }
});
}