Karplus-Strong with Web Audio API

pluck.js

function Pluck( ctx ) {
  this.sr = ctx.sampleRate;
  this.pro = ctx.createScriptProcessor( 512, 0, 1 );
  this.pro.connect( ctx.destination );
}

Pluck.prototype.play = function( freq ) {
  var N = Math.round( this.sr / freq ),
    impulse = this.sr / 1000,
    y = new Float32Array( N ),
    n = 0;
  this.pro.onaudioprocess = function( e ) {
    var out = e.outputBuffer.getChannelData( 0 ), i = 0, xn;
    for ( ; i < out.length; ++i ) {
      xn = ( --impulse >= 0 ) ? Math.random() - 0.5 : 0;
      out[ i ] = y[ n ] = xn + ( y[ n ] + y[ ( n + 1 ) % N ] ) / 2;
      if ( ++n >= N || !this.playing ) {
        n = 0;
      }
    }
  }.bind( this );
  this.playing = true;
};

Pluck.prototype.pause = function() {
  this.playing = false;
};

// usage:

var ctx = new webkitAudioContext(),
  pluck = new Pluck( ctx );
pluck.play( 220 );