how to take either String or numbers..in textbox

[madhuri kunchala]

hi,
in my project...in one of the textbox...i need to take either numbers or NULL..im not getting any idea..can anyone help me out..here is my jsp code and js code..

login.jsp

 

 <td><font color="#800000" size=""><b>L-Acct. No.</b></font></td>
 <td><input type="text" name="localAccNo" value=NULL></td>
 

login.js

  


if (document.frm.localAccNo.value == "")
    {
        alert("Enter Local A/c No. or 'NULL' in capitals");
        document.frm.localAccNo.focus();
        return (false);
    }
    var chkLocalAccNo = "0123456789";
    var chkLocalAccNoStr = document.frm.localAccNo.value;
    var allchkLocalAccNoValid = true;
    for (i = 0;  i < chkLocalAccNoStr.length;  i++)
    {
        ch = chkLocalAccNoStr.charAt(i);
        for (j = 0;  j < chkLocalAccNo.length;  j++)
            if (ch == chkLocalAccNo.charAt(j))
                break;
        if (j == chkLocalAccNo.length)
        {
            allchkLocalAccNoValid = false;
            break;
        }
    }
    if (!allchkLocalAccNoValid)
    {
        alert("Enter only numeric in the \" Local A/c No. \" field");
        document.frm.localAccNo.focus();
        return (false);
    }
 
 

and i need the output as

L-Acct. No.----> NULL
or
L-Acct. No.----> 123

thanks and waiting for the reply..
madhu.

[Chris Baron]

Check out the function isNaN() (is not a number).
If isNaN(123) is false, it's a number.

[madhuri kunchala]

hi,
i didnt understand the reply..

[Chris Baron]

Well you replace everything what's in your outer for-loop with:

if(isNaN(chkLocalAccNoStr.charAt(i))){
             allchkLocalAccNoValid = false;
             break;
}

If the AccNo must not begin with leading zeros, you can even replace the outer loop with a check for isNaN(chkLocalAccNoStr)

And before that all you check if chkLocalAccNoStr == 'NULL'.
If yes, you return true;