how to send addtional form data in froala editor through ajax request?

Question

I am using froala editor v2, and I need to save the form content through ajax request, so I am tried following way

HTML

<form enctype="multipart/form-data" id="composeForm" action="#" method="post">
     <input type="file" name="compose_attachments[]" id="file-7" class="inputfile theme-inputfile" accept=".jpg,.jpeg,.png,.xls,.xlsx,.csv,.pdf,.ppt,.doc,.docx" multiple />
<input type="text" class="form-control inputES" placeholder="Email Subject" name="compose_subject">
<input class="autoTags" type="text" value="" data-role="tagsinput" placeholder="" name="compose_to">
<input class="autoTags" type="text" value="" data-role="tagsinput" placeholder="" name="compose_cc">
<input class="autoTags" type="text" value="" data-role="tagsinput" placeholder="" name="compose_bcc">
<textarea class="froala-editor-mail" id="composeEmailBody" name="compose_body"></textarea>
<button type="button" class="btn btn-green-bs p-lr-30 mr-10" id="SendComposedEmail">SEND</button>
</form>

JS

<script>
var editor_compose = new FroalaEditor('#composeEmailBody', {
      // Set the save URL.
      saveURL: `${ajaxUrl}?method=sendTestEmail`,

      // HTTP request type.
      saveMethod: 'POST',

      saveParams: new FormData($("#composeForm")[0]),
      
      events: {
                    'save.before': function () {
                        // Before save request is made.
                        showLoader(0);
                    },

                    'save.after': function () {
                        // After successfully save request.
                        showLoader(1);
                    },

                    'save.error': function () {
                        // Do something here.
                        alert("Save error;");
                    }
      }
});
document.querySelector('#SendComposedEmail').addEventListener("click", function () {
      editor_compose.save.save();
});
</script>

PHP

<?PHP 
case 'sendTestEmail':
        echo "<pre>";print_r($_POST);print_r($_FILES);exit;
    break;
?>

OUTPUT

Array
    (
    )

$_POST & $_FILES are empty and only got by editor HTML value.

so, I am not able to get formData in ajax request. how to resolve it??