javascript know form is submitted or not code example

Example 1: js form submit listener

document.getElementById("#myFormId").addEventListener("submit", function(e){
    if(!isValid){
        e.preventDefault();    //stop form from submitting
    }
  	//do whatever an submit the form
});

Example 2: how to access values from a form event callback

<form_instance_or_returned_event_on_callback>.elements[0].value