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;//就密码
var newLogPWD = document.InfoForm.newLogPWD;//新密码
var confirmLogPWD = document.InfoForm.confirmLogPWD;//确认密码

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>