Javascript validation:Block special characters

Question

Hi Buddies,

How can i restrict users fro entering special characters in the text box.I want only numbers and alphabets to be entered ( Typed / Pasted ) Any Samples ?

Thanks in advance

Answer 1

Basically, just use an appropriate onkeypress handler. See http://www.qodo.co.uk/blog/javascript-restrict-keyboard-character-input/ and the example http://www.qodo.co.uk/wp-content/uploads/2008/05/javascript-restrict-keyboard-character-input.html

Answer 2

It would help you... assume you have a form with "formname" form and a text box with "txt" name. then you can use following code to allow only aphanumeric values

var checkString = document.formname.txt.value;
if (checkString != "") {
    if ( /[^A-Za-z\d]/.test(checkString)) {
     alert("Please enter only letter and numeric characters");
     document.formname.txt.focus();
     return (false);
    }
}

Answer 3

You have two approaches to this:

1. check the "keypress" event. If the user presses a special character key, stop him right there
2. check the "onblur" event: when the input element loses focus, validate its contents. If the value is invalid, display a discreet warning beside that input box.

I would suggest the second method coz its less irritating.

Additionally, I will also suggest that you reconsider if you really want to prevent users from entering special characters. Because many people have $, #, @ and * in thier passwords.

I presume that this might be in order to prevent SQL injection; if so: its better that you handle the checks server-side. Or better still, escape the values and store them in the database.

cheers, jrh.

Answer 4

i need to see the method of special character validation in javascript