How to prevent user from entering special character in text field of form?

Question

I am trying to prevent user from entering special character like (!,@,&)

Following code restrict user to enter above character only if it is first character after that it allows user to enter above character.

for example & can not be entered but A& can be entered

$('input#first_name-required').bind('keypress', function(e) {
    console.log( e.which );
    if($('input#first_name-required').val().length == 0){
        var k = e.which;
        var ok = k >= 65 && k <= 90 || // A-Z
            k >= 97 && k <= 122 || // a-z
            k >= 48 && k <= 57 //0-9 ;

        if (!ok){
            e.preventDefault();
        }
    }
}); 

Answer 1

if($('input#first_name-required').val().length == 0)

Just remove this condition and it should work fine.

.val() returns the string inside of the input. .length == 0 practically means "if the string is 0 characters long". You validation only runs when the input is empty, thus only when you type the first character.

Answer 2

You have added if condition. I think you might want to check for length grater than 0

 $('input#first_name-required').bind('keypress', function(e) { var k = e.which; var ok = k >= 65 && k <= 90 || // AZ k >= 97 && k <= 122 || // az k >= 48 && k <= 57 //0-9 ; if (!ok){ e.preventDefault(); } }); 

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <input id="first_name-required">