createNewDiscussion/createNewDiscussionReply via JSOM in SharePoint Discussion Board from external Angular SPA - sharepoint

Question

Scenario:
I have an Angular SPA and a SharePoint 2013, installed in separated servers. I would like to consume a SharePoint discussion board in my SPA, means I would like to use my customized UI to perform CRU(D) operations on the SharePoint discussion board.
Through some workarounds I already achieved this objective using the SP REST API, but unfortunately since REST API doesn't allow setting some parameters for the discussion board (in particular the ParentID) I am not really able to use REST API in a satisfactory way.
In order to make it possible to work through the REST API I had to change the configuration in the IIS of the SharePoint Server to rewrite the headers and allow the Cross-Domains Call. Moreover I pass as options in the http call the digest from the context info. As I said, the comunication works, I can create new discussions or replies, but these are malformed because the API itself doesn't offer the methods that I need, but just some workaround to post not-so-good-looking messages in the discussion board (for example the threading is completely lost).
With JSOM I am doing this (I simpliefied a bit):
createReply() {
let clientContext = new SP.ClientContext("otherserver.sharepoint.com");
    let list = clientContext.get_web().get_lists().getByTitle("myDiscussionBoardName");
    let discussionItem = list.getItemById(parentTopicId); //eg. parentTopicId === 10
    let properties = {'Body': 'My Message'};
    let messageItem = SP.Utilities.Utility.createNewDiscussionReply(clientContext, discussionItem);
    for (var propName in properties) {
messageItem.set_item(propName, properties[propName])
    }
messageItem.update();
    clientContext.executeQueryAsync(() => 
{ console.log("Gotcha!", messageItem); },
  (error: any) => { console.log('Request failed', error); });
  }
But unfortunately I get a 401 error. My understanding would also be that I won't need to provide a digest, since JSOM should take care of it by itself, but I am not sure of this, nor I am aware of how I could provide the digest within a JSOM call.
Honestly this message is my last hope to get to the bottom of this. I actually am already planning to use different solutions, but I can't believe that a solution doesn't exist, in particular because using a local proxy (sp-rest-proxy, you may know it well if you develop angular application based on SP) the connection somehow works correctly.

Answer 1

check the below link and also I just put one the example from our code
http://sharepointsanjay.blogspot.com/2016/05/how-to-refresh-request-digest-token.html
var headers = {
"Accept": "application/json; odata=verbose",
"Content-Type": "application/json; odata=verbose",
"X-RequestDigest": document.getElementById("__REQUESTDIGEST").value,
"X-HTTP-Method": "MERGE",
"If-Match": "*"
};
return $http({
headers: headers,
method: "POST",
url: url,
data: JSON.stringify(data)
}).then(complete, failed);