bootstrap 4 form validator with jquery

1$(document).ready(function() {
2  $("#submitButton").click(function() {
3    //Fetch form to apply custom Bootstrap validation
4    var form = $("#signup-form");
5
6    if (form[0].checkValidity() === false) {
7      event.preventDefault();
8      event.stopPropagation();
9    }
10    
11    form.addClass('was-validated');
12
13    //Make ajax call here
14  })
15})