网页表格中查出的数字是文本格式如何排序
在网上找了如下代码实现了网页表格的排序，但是在数据库中查出的数字以文本存储，数字的排序问题无法解决，问下该如何实现排序？
<SCRIPT language=JavaScript>
var dom = (document.getElementsByTagName) ? true : false;
var ie5 = (document.getElementsByTagName && document.all) ? true : false;
var arrowUp, arrowDown;
if (ie5 || dom)
 initSortTable();
function initSortTable() {
 arrowUp = document.createElement("SPAN");
 var tn = document.createTextNode("↓");
 arrowUp.appendChild(tn);
 arrowUp.className = "arrow";
 arrowDown = document.createElement("SPAN");
 var tn = document.createTextNode("↑");
 arrowDown.appendChild(tn);
 arrowDown.className = "arrow";
}
function sortTable(tableNode, nCol, bDesc, sType) {
 var tBody = tableNode.tBodies[0];
 var trs = tBody.rows;
 var a = new Array();
 
 for (var i=0; i<trs.length; i++) {
  a[i] = trs[i];
 }
 
 a.sort(compareByColumn(nCol,bDesc,sType));
 
 for (var i=0; i<a.length; i++) {
  tBody.appendChild(a[i]);
 }
}
function CaseInsensitiveString(s) {
 return String(s).toUpperCase();
}
function parseDate(s) {
 return Date.parse(s.replace(/\-/g, '/'));
}
function toNumber(s) {
  return Number(s.replace(/[^0-9\.]/g, ""));
}
function compareByColumn(nCol, bDescending, sType) {
 var c = nCol;
 var d = bDescending;
 
 var fTypeCast = String;
 
 if (sType == "Number")
  fTypeCast = Number;
 else if (sType == "Date")
  fTypeCast = parseDate;
 else if (sType == "CaseInsensitiveString")
  fTypeCast = CaseInsensitiveString;
 return function (n1, n2) {
  if (fTypeCast(getInnerText(n1.cells[c])) < fTypeCast(getInnerText(n2.cells[c])))
  return d ? -1 : +1;
  if (fTypeCast(getInnerText(n1.cells[c])) > fTypeCast(getInnerText(n2.cells[c])))
  return d ? +1 : -1;
  return 0;
 };
}
function sortColumn(e) {
 var tmp, el, tHeadParent;
 if (ie5)
  tmp = e.srcElement;
 else if (dom)
  tmp = e.target;
 tHeadParent = getParent(tmp, "THEAD");
 el = getParent(tmp, "TH");
 if (tHeadParent == null)
  return;
 
 if (el != null) {
  var p = el.parentNode;
  var i;
  if (el._descending) // catch the null
  el._descending = false;
  else
  el._descending = true;
 
  if (tHeadParent.arrow != null) {
  if (tHeadParent.arrow.parentNode != el) {
  tHeadParent.arrow.parentNode._descending = null;  
  }
  tHeadParent.arrow.parentNode.removeChild(tHeadParent.arrow);
  }
  if (el._descending)
  tHeadParent.arrow = arrowDown.cloneNode(true);
  else
  tHeadParent.arrow = arrowUp.cloneNode(true);
  el.appendChild(tHeadParent.arrow);
  
  // get the index of the td
  for (i=0; i<p.cells.length; i++) {
  if (p.cells[i] == el) break;
  }
  var table = getParent(el, "TABLE");
  // can't fail
 
  sortTable(table,i,el._descending, el.getAttribute("type"));
 }
}
function getInnerText(el) {
 if (ie5) return el.innerText; //Not needed but it is faster
 
 var str = "";