wavesurfer.js/example/microphone/app.js

Interactive navigable audio visualization using Web Audio and Canvas

'use strict';

// Create an instance
var wavesurfer = Object.create(WaveSurfer);

// Init & load
document.addEventListener('DOMContentLoaded', function () {
    var options = {
        container     : '#waveform',
        waveColor     : 'black',
        loopSelection : false,
        cursorWidth   : 0
    };

    // Init wavesurfer
    wavesurfer.init(options);

    // Init Microphone plugin
    var microphone = Object.create(WaveSurfer.Microphone);
    microphone.init({
        wavesurfer: wavesurfer
    });

    // start/stop mic on click
    document.querySelector('#micBtn').onclick = function() {
        if (microphone.active) {
            microphone.stop();
        } else {
            microphone.start();
        }
    };
});