function formCheck() {
if (document.theform.strno.value == "")
{
alert("请输入车次！");
return false; 
}
nr1=document.theform.strno.value; 
flg=0; 
str=""; 
spc="";
arw=""; 
for (var i=0;i<nr1.length;i++){ 
cmp="0123456789tkTKnNzZ" 
tst=nr1.substring(i,i+1) 
if (cmp.indexOf(tst)<0){ 
flg++; 
str+=" "+tst; 
spc+=tst; 
arw+="^"; 
} 
else{arw+="_";} 
} 
if (flg!=0){ 
if (spc.indexOf(" ")>-1) { 
str+="和空格"; 
} 
alert("这里只接受数字或t/T、k/K、z/Z与n/N数字的组合，发现"+flg+"个不可接受的字符:\n"+str); 
return false; 
} 
}