How to allow alphanumeric in txtbox using javascript in.net?

Question

I have one textbox thats allow alphanumeric if user enters symbols show the alert message

'You have enter symbol do you want to continue'

 'yes/no

 

If click yes symbol is allowed.if click no symbol is not allowed. 

Answer 1

Go with regular Expression it might be helpful

$('#text').keypress(function (e) {
    var regex = new RegExp("^[a-zA-Z0-9]+$");
    var str = String.fromCharCode(!e.charCode ? e.which : e.charCode);
    if (regex.test(str)) {
        return true;
    }
    e.preventDefault();
    return false;
});