Form dirty check

$('form.claim-details input, form select, form textarea').each(function () {
                this.backup = this.value;
            });
            $('form.claim-details').on('change keyup', 'input,select,textarea', function () {
                if (this.value !== this.backup) {
                    this.backup = this.value;
                    this.form.isDirty = true;
                    //$(this).addClass('field-dirty');
                    //$(this.form).addClass('form-dirty');
                    //console.log('form is dirty');

                    var msisdn = $('#id_object_id').text().trim(),
                        accountNo = $('#id_account_number').val();

                    if (msisdn === accountNo) $('#save-changes-btn').removeAttr('disabled');
                }
            });