renderer.js

// This file is required by the index.html file and will
// be executed in the renderer process for that window.
// No Node.js APIs are available in this process because
// `nodeIntegration` is turned off. Use `preload.js` to
// selectively enable features needed in the rendering
// process.
player = document.getElementById("player");
btnPlay = document.getElementById("btnPlay");
btnPause = document.getElementById("btnPause");
btnVolMore = document.getElementById("btnVolMore");
btnVolLess = document.getElementById("btnVolLess");
lblDuration = document.getElementById("lblDuration");
lblSource = document.getElementById("lblSource");

start();

// Salvar dados
function saveData(key, value) {
  return localStorage.setItem(key, value);
}

// Salvar dados
function loadData(key) {
  return localStorage.getItem(key);
}

// Botão que diminui o volume
btnVolLess.addEventListener("click", function() {
  player.volume = player.volume - 0.01;
  player.volume < 0.01 ? (player.volume = 0) : player.volume;
  saveData("volume", player.volume);
  currentVolume();
});

// Botão que aumenta o volume
btnVolMore.addEventListener("click", function() {
  player.volume = player.volume + 0.01;
  saveData("volume", player.volume);
  currentVolume();
});

// Botão que executa a faixa
btnPlay.addEventListener("click", function() {
  player.play();
});

// Botão que para a faixa
btnPause.addEventListener("click", function() {
  player.pause();
});

// Controla o text do volume
function currentVolume() {
  lblVolume.innerText = Math.round(player.volume * 100);
}

// Verifica o tempo corrente da música
function currentTime() {
  let date = new Date(0);
  date.setSeconds(player.currentTime); // specify value for SECONDS here
  lblDuration.innerText = date.toISOString().substr(11, 8);
}

// Função de atualização em tempo real
setInterval(timeExecute, 500);
function timeExecute() {
  currentTime();
}

// Configurações executadas ao iniciar
function start() {
  parseFloat(loadData("volume"))
    ? (player.volume = parseFloat(loadData("volume")))
    : (player.volume = 0.2);
  currentVolume();
  currentTime();
}