Help with Extension

Good afternoon, tell me how to get only the “_value” variable from here [
{“_id”:“E0BB0C-WICATAXR-E0%3ABB%3A0C%3A00%3A25%3A6C”,“VirtualParameters”:{“mac”:{“_object”:false,“_timestamp”:“2024-02-27T14: 54:05.233Z”,“_type”:“xsd:string”,“_value”:“E0:BB:0C:00:25:6C”,“_writable”:false}}}
I tried to adjust the template a little

“use strict”;
const http = require(“http”);
let cache = null;
let cacheExpire = 0;
function getMAC(args, callback) {
if ( < cacheExpire) return callback(null, cache);
.get(“{“_tags”%3A"NEW"}&projection=VirtualParameters.mac”, (res) => {
if (res.statusCode !== 200)
return callback(
new Error(Request failed (status code: ${res.statusCode}))
let rawData = “”;
res.on(“data”, (chunk) => (rawData += chunk));
res.on(“end”, () => {
let MACAddress = JSON.parse(rawData)[“mac”];
cache = [MACAddress[“_value”]];
cacheExpire = + 10000;
callback(null, cache);
.on(“error”, (err) => {
exports.getMAC = getMAC

const mac = ext(“test”, “getMAC”);
return {writable: false, value: [mac, “xsd:string”]};

But when I try to declare a value in VirtualParameters I get the error Invalid virtual parameter value attribute

You appear to have some sort of amalgamation of code you have pieced together without understanding what any of it does.

The example docs for virtual params cover a unified mac address.