i have html code with JS in it, i have a problem that the submit button not giving me an alert window, can you correct my code?

this is part of my code:

Degree:

                <script>
                    function F2(){
                        var y = document.getElementById("dd");
                            if (y>=73){
                            window.alert("Your degree is less then required");
                            }
                    }
                </script>

it's in a form, i hope someone help me in my code.