Eval.user.js

// ==UserScript==
// @name        Eval
// @namespace   Violentmonkey Scripts
// @match       https://multiplayerpiano.net/*
// @grant       none
// @version     1.0
// @author      Hri7566
// @description 4/21/2023, 7:12:33 AM
// ==/UserScript==

MPP.client.on("a", msg => {
  if (msg.p._id !== MPP.client.getOwnParticipant()._id) return;
  if (!msg.a.startsWith(">")) return;
  let out;
  try {
    out = eval(msg.a.substring(1));
  } catch (err) {
    out = `❌ ${err}`;
  }

  MPP.client.sendArray([{m: 'a', message: `\u034f✔️ ${typeof out} ${out}`}])
});