Java script validation symbol % must not allow in text field

Question

I am working in javascript. I want to add validation on my text field that only characters are allowed.

along with characters, I allowed left arrow key which has keycode 37. But this is creating problem because keycode of % is also 37. And I dont want to allow % symbol.

Please suggest me how can I differenciate % and left arrow key , because both key code are 37 ?

Answer 1

If you press the 'percent' key the char code is 37, for the 'left arrow'-key it's not 37; eg:

$('#test').keypress(function(oEvent) {
    if (oEvent.charCode == 37) {
        return false;
    }
});

Also see this jsfiddle .

=== UPDATE ===

For additional internet explorer support:

$('#test').keypress(function(oEvent) {
    var iCode = typeof oEvent.charCode == 'number' ? oEvent.charCode : oEvent.keyCode;
    if (iCode == 37) {
        return false;
    }
});

Also see this jsfiddle .

Answer 2

Don't limit the keypresses for validation. People can just copy/paste to overcome that.

You need to use Regex so validate your input.

Learn more about it from https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/RegExp

Answer 3

You should validate your user input after the user submits the form. You can write a function that the form's "onsubmit" attribute runs before the data is submitted to the server, or you can set the form action to "action='javascript:someFunction()'" either way will work. Disallowing keystrokes makes the user interface more complicated and cumbersome for the end user and poses security risks for xss or injection attacks. I would advise checking user input with javascript and returning an error message if it is invalid, then on the server side validating the data once more, and sanitizing the data.