How do I get a specific key value from JSON object

This is my first time using any kind of APIs, and I’m just starting out in JS. I want to get the status of a server within a server hosting panel, to do this I need to log in (API/Core/Login), get a the value of a key called sessionID, then send that value to /API/Core/GetUpdates to get a response. When trying to pass the sessionID to GetUpdates, it sends undefined instead of the sessionID, I’m guessing I’m doing something wrong when trying to reference the key value. Here’s my code:

var loginurl = "https://proxyforcors.workers.dev/?https://the.panel/API/ADSModule/Servers/83e9181/API/Core/Login";

var loginRequest = new XMLHttpRequest();
loginRequest.open("POST", loginurl);

loginRequest.setRequestHeader("Accept", "text/javascript");
loginRequest.setRequestHeader("Content-Type", "application/json");

loginRequest.onreadystatechange = function() {
  if (loginRequest.readyState === 4) {
    console.log(loginRequest.status);
    console.log(loginRequest.responseText);
  }
};

var logindata = '{"username":"API", "password":"password", "token":"", "rememberMe":"true"}';

loginRequest.send(logindata);

var statusurl = "https://proxyforcors.workers.dev/?https://the.panel/API/ADSModule/Servers/83e9181/API/Core/GetUpdates";

var statusreq = new XMLHttpRequest();
statusreq.open("POST", statusurl);

statusreq.setRequestHeader("Accept", "text/javascript");
statusreq.setRequestHeader("Content-Type", "application/json");

statusreq.onreadystatechange = function() {
  if (statusreq.readyState === 4) {
    console.log(statusreq.status);
    console.log(statusreq.responseText);
  }
};

var statusdata = `{"SESSIONID":"${loginRequest.responseText.sessionID}"}`; // Line I'm having problems with

statusreq.send(statusdata);

console.log(loginRequest.responseText.sessionID)

Here’s the response of /API/Core/Login

{"success":true,"permissions":[],"sessionID":"1d212b7a-a54d-4e91-abde-9e1f7b0e03f2","rememberMeToken":"5df7cf99-15f5-4e01-b804-6e33a65bd6d8","userInfo":{"ID":"034f33ba-3bca-47c7-922a-7a0e7bebd3fd","Username":"API","IsTwoFactorEnabled":false,"Disabled":false,"LastLogin":"/Date(1639944571884)/","GravatarHash":"8a5da52ed126447d359e70c05721a8aa","IsLDAPUser":false},"result":10}

Any help would be greatly appreciated, I’ve been stuck on this for awhile.