Allow Only White Space, Letters, Backspace, and Tab

I'm using FireFox to test my script out. My goal is to allow white space, letters, backspace and tab to work, but for some reason i could break my code and type in a number which i don't want. How can i fix this issue? This is what i have so far. Please let me know how i could modify this code to make it work the way i want it to.

                $(document).ready(function () {
                    $("#inputTextBox").keypress(function (event) {
                        var inputValue = event.which;

                        //Backspace ASCII = 8 
                        //Tab ASCII = 9 
                        if (!(inputValue >= 65 && inputValue <= 123)) {
                            if (inputValue === 8 && inputValue === 9){
                                event.preventDefault();
                            }
                        }
                        console.log(inputValue);
                    });