Question

hello i am using javascript to validate field

i am checking special characters.. the code i am implementing validates all the special characters except _ underscore..

   <script type="text/javascript" language="javascript">
function validateForm()
{
    var iChars = "!@#$%^&*()+=-[]\\\';,./{}|\":<>?_";

   for (var i = 0; i < document.reg_form.txtusername.value.length; i++) 
        {
            if (iChars.indexOf(document.reg_form.txtusername.value.charAt(i)) != -1) 
                {
                    alert ("Special Characters are not allowed.");
                    return false;
                        }
         }
    return true;
}
</script>

for this filed

<input name="txtusername" type="text" id="txtusername" maxlength="10" style="background-color:#CCC"  />

but its not validating the underscore

Answer 1

characters in strings can be addressed as if the string were an array (which, if you think about it, it is). Since you’re looping through the string char-per-char, again, as you would with an array, why not be consistent in your logic?

if (iChars.indexOf(document.reg_form.firstname.value[i]) !== -1)
{
    alert('Foobar');
    return false;
}

That should work… Also: there’s no real need to escape the single quote, since the iChar string is delimited by double quotes… if all else fails, you might want to try omitting that backslash, too. Though I don’t think that’s what’s causing the problem

It is working: here