TamperMonkey user script to set text content

gistfile1.txt

// ==UserScript==
// @name         Rewrite words
// @description  Rewrite words
// @grant        GM_log
// @match        *://*/*
// @version      1
// ==/UserScript==


setInterval (function() { doReplace() }, 1000);

function doReplace() {
    try {
        document.querySelector('#mm-player-username').textContent = "xxx"
    } catch (error) {
    }
}