Javascript: call a blocking HTTP POST [duplicate]

Question

I have a caller function that invokes another function that send a HTTP POST with parameters. Now i want that this called function blocks execution until there is its "success" (so when its HTTP POST has been done).

This is my logical code:

var fingerprint = null;
var janus_session = null;
var inserted = "false";

$(document).ready(function() {
      //stuff
      fingerprint = FindFingerprint(jsep);

      janus_session = janus.getSessionId();
      inserted = SendSDPLine(fingerprint, janus_session);
      console.log("**in MAIN: inserted= " + inserted);

      //other stuff
    }

function SendSDPLine(fingerprint, janus_session) {
  var sdp = fingerprint;
  //    var url = "http://localhost:8484/Shine/AccountController";
  var action_type = "InsertSDPLine";
  var sessionid = janus_session;

  $.ajax({
    type: "POST",
    url: url,
    xhrFields: {
      withCredentials: false
    },
    data: {
      "action": action_type,
      "sdpline": fingerprint,
      "sessionid": sessionid
    },
    success: function(data) {
      if (data == "INSERTED") {
        inserted = "true";
        console.log("in SENDSDPLINE: inserted= " + inserted);
      }
      return inserted;
      //        return checkFingerprint (fingerprint);
    },
    // vvv---- This is the new bit
    error: function(jqXHR, textStatus, errorThrown) {
      console.log("Error, status = " + textStatus + ", " +
                  "error thrown: " + errorThrown);
    }
  });

}

In few words, i want that other stuff has been executed after that HTTP POST response has been checked. I've already seen another problem: initially, inserted has false value. In success(data) in HTTP POST response, it has true value. But, in the caller function, in the following console.log has undefined value.

So, i have two question:

1. how to return this value to the caller function
2. how to stop execution of the caller function until HTTP POST response has been received?

Answer 1

If you need to block the execution until AJAX returns, you can specify async:false in ajax parameters, as per jQuery documentation.