Cruxade's Data validation library

I am beginning to create a data validation library under Cruxade. I'll be happy to have your contribution to the code and make it better.

function isBlank(c){
 if (null==c) return true;
 return c.search(/^\s*$/)!=-1; 
}

function trimSpaces(c){
 if (null==c) return "";
 if (isBlank(c)) return "";
 c=c.replace(/^\s+/,"");
 c=c.replace(/\s+$/,"");
 return c;
}

function isDigit(n){
  if (null==n) return false;
  if (typeof n == "number") return true;
  n = trimSpaces(n);
  return n.search(/^\d+\.*\d*$/)!=-1; 
}

function isDate(d){
 if (null==d) return false;
 if (d instanceof Date) return true;
 d = trimSpaces(d);
 if (d.search(/^\d+-\d+-\d+$/)==-1) return false;
 var lv_nYear = parseInt(d.match(/^\d+/));
 var lv_cMonth = String(d.match(/-\d+-/));
 lv_nMonth = parseInt(lv_cMonth.match(/\d+/));
 lv_cDay = String(d.match(/-\d+$/));
 lv_nDay = parseInt(lv_cDay.match(/\d+/));
 
 // check for leap year and if day corresponds to month
 if (lv_nYear < 1) return false;
 if ((lv_nMonth < 1 ) || (lv_nMonth > 12)) return false
 if ((lv_nDay < 1) || (lv_nDay > 31)) return false;
 if (lv_nMonth==2){
  if (lv_nDay<=28) return true;
  if (lv_nDay>29) return false;
  var lv_nScore= 0;
  lv_nScore = (lv_nYear % 400==0)?1:0;
  if (lv_nScore==0){
   lv_nScore = (lv_nYear % 100==0)?-100:0;
   lv_nScore = lv_nScore + ((lv_nYear % 4 ==0)?3:0);
  }
  return lv_nScore > 0; 
 }
 if (lv_nDay==31){
  var lv_c30month={};
  lv_c30month[4]="";
  lv_c30month[6]="";
  lv_c30month[9]="";
  lv_c30month[11]="";
  return !(lv_nMonth in lv_c30month);
 }
 return true; 
}
:-)

edited: 2008-06-06