how to call the function only when form is submit in jquery code example

Example 1: jquery prevent form submit

//option A
    $("form").submit(function(e){
        e.preventDefault();
    });

Example 2: jQuery AJAX form submit

// jQuery ajax form submit example, runs when form is submitted
$("#myFormID").submit(function(e) {
    e.preventDefault(); // prevent actual form submit
    var form = $(this);
    var url = form.attr('action'); //get submit url [replace url here if desired]
    $.ajax({
         type: "POST",
         url: url,
         data: form.serialize(), // serializes form input
         success: function(data){
             console.log(data);
         }
    });
});