Prevent double submission of forms in Submit

Question

How can I prevent the user from doing multiple submissions of a form? My code is like this:

// VALIDAÇÃO DO CADASTRO
$(document).ready(function(e){          
    $(function () {
        // VALIDAÇÃO
        $("#frmCadastro").validate({                        
            rules: {    
               IdUnicoop: {
                  required: true
               }
            },                      
            messages: {
               IdUnicoop: {
                  required: ""
               } 
            },
            // Do not change code below
            errorPlacement: function (error, element) {
                error.insertAfter(element.parent());
            },
            submitHandler: function (form) {
                var form = $("#frmCadastro");
                var formdata = false;
                
                if (window.FormData){
                      formdata = new FormData(form[0]);
                }
                
                $.ajax({
                    type: 'POST',
                    url: 'pAddEstagio.php',
                    data: formdata ? formdata : form.serialize(),
                    dataType: 'json',                                
                    cache: false,
                    contentType: false,
                    processData: false,                                
                    beforeSend: function () {
                        // $("#msgResult").html('AVISO! Enviando...');
                    },
                    success: function (response) {
                        e.preventDefault(); 
                        if (response.codigo == "1") {                                        
                            bootbox.alert({
                                message: response.mensagem,
                                callback: function () {
                                    window.location.href = "iAddEstagio.php";
                                }
                            })                                  
                        } else { 
                            e.preventDefault();                                        
                            bootbox.alert({
                                message: response.mensagem,
                                callback: function () {
                                    window.location.href = "iAddEstagio.php";
                                }
                            })                                                                                  
                        }                                
                    },
                    error: function (xhr, ajaxOptions, thrownError) {
                        console.log(xhr, ajaxOptions, thrownError);
                        
                        bootbox.alert({
                            message: "ATENÇÃO! Ocorreu um erro ao tentar enviar a solicitação. Contate o suporte técnico.",
                        })                                     
                        
                         // $("#msgResult").html('ATENÇÃO! Ocorreu um erro ao tentar enviar a solicitação. Contate o suporte técnico.');
                    }
                });
                return false;
            }
        });
    });
}); 

I tried to use the preventDefault but without success.

Answer 1

Try to put an attribute in the form onSubmit="return false" after you have made your validations remove the attribute onSubmit and call .submit() for your form as you suspended the automatic Submit will need to do manually.