js验证密码必须为大小写字母和数字组成

<script language="JavaScript" type="text/JavaScript">
function checkPass(pass){
 if(pass.length < 6){  return 0; }
 var ls = 0;
 if(pass.match(/([a-z])+/)){  ls++; }  
 if(pass.match(/([0-9])+/)){  ls++; }  
 if(pass.match(/([A-Z])+/)){   ls++; }  
 if(pass.match(/[^a-zA-Z0-9]+/)){ ls++;}  
 return ls;
}  

function Validate(){
 var oldLogPWD = document.InfoForm.oldLogPWD;
 var newLogPWD = document.InfoForm.newLogPWD;
 var confirmLogPWD = document.InfoForm.confirmLogPWD;

 if(oldLogPWD.value.checkEmpty()){
   alert("旧登录密码不能为空!")
   oldLogPWD.focus();
   return false;
 }
if(newLogPWD.value.checkEmpty()){
  alert("新登录密码不能为空!")
  newLogPWD.focus();
  return false;
 }
if(checkPass(newLogPWD.value)<3){
  alert("新登录密码复杂度不够，请重新设置！");  
  newLogPWD.focus();  
  return false ;  
 }
if(newLogPWD.value!=confirmLogPWD.value){
  alert("确认新登录密码必须和新登录密码相等!");
  confirmLogPWD.focus();
  return false;
 }
if(newLogPWD.value==oldLogPWD.value){
    alert("新登录密码不可以与旧登录密码相等!");
    newLogPWD.focus();
    return false;
 }
 return true;
}


function SubmitForm(){
 if(Validate()){
 var con;
 con=confirm("请牢记您的密码,确认执行该操作吗？");
 if(con==true){
  document.InfoForm.submit();
  }
 }
}

</script>