If you control the playback and mute of music through js

I am a beginner in programming. I would like to ask if I write a music player that I want to be able to click to play and click again to mute. How should I write it? I

have tried several times and failed.

PS. Because I don’t know how to put the music file on the Internet, the current music file is invalid, it is purely indicative.

//關閉
let tag = true;
let music = document.querySelector('#music');
let btn = document.querySelector(".btn");
btn.addEventListener("click", function () {
    // 如果目前 flag 不是關閉就撥放
    if (tag) {
    // music.pause();
    music.setAttribute("muted","true");
    btn.setAttribute("class", "pause");
    tag = false;
    } else {
    music.play();
    btn.setAttribute("class", "play");
    tag = true;
    }
});

body{
  height: 500vh;
}
.btn {
  width: 60px;
  height: 60px;
  background-image: url('https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcTmxXsF6UrJ0o-wcYdmXOqSpxZXhMzgcCzyAA&usqp=CAU');
  background-size: cover;
}

.play{
  width: 60px;
  height: 60px;
  border-radius: 50%;
  transition: 1s;
  background-image: url('https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcTmxXsF6UrJ0o-wcYdmXOqSpxZXhMzgcCzyAA&usqp=CAU');
  background-size: cover;
}

.pause {
  width: 60px;
  height: 60px;
  border-radius: 50%;
  transition: 1s;
  background-image: url('https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcScVjEwKCmnfciiCoEZ6am7ZXoIaVR0rUE_O2H1xWkqDMOZV-mk7i8eMwktqV9nHCsyF3A&usqp=CAU');
  background-size: cover;
}

<audio id="music" controls="controls">
  <source src="demo.mp3" type="audio/mp3">
</audio>
<div class="btn"></div>