web-audio-peak-meter/examples/audio.js

A customizable peak meter using the web audio API

const audioCtx = new AudioContext();
const audioElement = document.getElementById('the-audio');
const meterElement = document.getElementById('peak-meter');

const sourceNode = audioCtx.createMediaElementSource(audioElement);
sourceNode.connect(audioCtx.destination);

const buttonElement = document.getElementById('ctx-button');
buttonElement.addEventListener('click', () => {
  if (audioCtx.state === 'suspended') {
    audioCtx.resume();
  } else {
    audioCtx.suspend();
  }
});

const ctxStatus = document.getElementById('ctx-status');
setInterval(() => {
  ctxStatus.innerText = audioCtx.state;
  if (audioCtx.state === 'suspended') {
    buttonElement.innerText = 'Resume';
  } else {
    buttonElement.innerText = 'Suspend';
  }
}, 100);

const test = new webAudioPeakMeter.WebAudioPeakMeter(sourceNode, meterElement);