在提交时发出验证表单

我正在尝试在提交时验证电子邮件。现在，我有它的工作，使它验证，如果我从电子邮件标签提交按钮，也如果我直接点击提交按钮。但是，如果我在电子邮件字段内按Enter键，则不验证。此外，一旦它确认点击提交，我必须再次点击按钮来实际提交。

原因是我在提交输入中以type="button"而不是type="submit"开头。这是因为当我开始使用type="submit"时，不管电子邮件是否有效，它都会提交。

现在，我从type="button"开始，验证电子邮件，然后在有效的电子邮件中将其更改为type="submit"。然而，就像我提到的，它仍然不是最用户友好的(即使它可以正常工作)。我想添加上面描述的用户友好特性。这里是我的代码(注意:我使用Mailgun jQuery邮件验证器的验证部分):

<form accept-charset="UTF-8" id="icpsignup" name="icpsignup" action="process.php" method="post">
    <p>                              
     <input type="text" onfocus="this.value=''" onblur="this.value=!this.value?'Enter name...':this.value;" class="txtbox_index" placeholder="Enter name..." value="Enter name..." name="fields_fname" id="fields_fname">
    </p>                                                                                 
    <p>                                            
     <input type="text" class="txtbox_index" onfocus="this.value=''" onblur="this.value=!this.value?'Enter email...':this.value;" name="fields_email" id="fields_email" Value="Enter email..." placeholder="Enter email...">
     <input type="text" style="border: none;color: #fff;cursor: none; background-color:transparent; height:0px;" size="1" value="<?=$country_field;?>" name="fields_country" id="fields_country">
   </p>
     <div id="status"></div>                                            
   <p class="forfree">                                              
     <input type="button" value="Signup For Free!" id="validate_submit" class="signupbtn_new" name="submit">
   </p>
     <input type="hidden" value="<?php echo $paramstring ;?>" name="fields_trk">
</form>   
<script src="js/vendor/jquery.js"></script>
<script src="js/mailgun_validator.js"></script>
<script>
      // document ready
      $(function() {
        // capture all enter and do nothing
       /* $('#fields_email').keypress(function(e) {
          if(e.which == 13) {
            $('#fields_email').trigger('focusout');
            return false;
          }
        });
        // capture clicks on validate and do nothing
       /* $("#validate_submit").click(function() {
          return false;
        });*/
        // attach jquery plugin to validate address
        $('#fields_email').mailgun_validator({
          api_key: 'pubkey-8s-e-ovj0nbi32xw5eeyibrmv-lkq2e2', // replace this with your Mailgun public API key
          in_progress: validation_in_progress,
          success: validation_success,
          error: validation_error,
        });
      });

      // while the lookup is performing
      function validation_in_progress() {
        $('#status').html("<img src='images/loading.gif' height='16'/>");
      }

      // if email successfull validated
      function validation_success(data) {
        $('#status').html(get_suggestion_str(data['is_valid'], data['did_you_mean']));
      }

      // if email is invalid
      function validation_error(error_message) {
        $('#status').html(error_message);
      }

      // suggest a valid email
 submitHandler: function(form) {
      function get_suggestion_str(is_valid, alternate) {
        if (alternate) {
          form.preventDefault();
          return '<span class="warning">Did you mean <em>' + alternate + '</em>?</span>';
        } else if (is_valid) {
          form.submit();
          //return '<span class="success">Address is valid.</span>';
        } else {
          form.preventDefault();     
          return '<span class="error">Address is invalid.</span>';
        }
      }
}

//尝试使用submitthandler的另一个版本。我不确定我是否应该使用验证。:

$(function() {
  $("#icpsignup").validate({
 submitHandler: function('icpsignup') {
      function get_suggestion_str(is_valid, alternate) {
        if (alternate) {
          icpsignup.preventDefault();
          return '<span class="warning">Did you mean <em>' + alternate + '</em>?</span>';
        } else if (is_valid) {
          icpsignup.submit();
          //return '<span class="success">Address is valid.</span>';
        } else {
          icpsignup.preventDefault();     
          return '<span class="error">Address is invalid.</span>';
        }
      }}
    })
})

    </script>