Question

It triggers twice all the time with different values…

This is my code:

window.onload = function init() {
  console.log('subscribing')
  player.observe(models.EVENT.CHANGE, function (e) {
    console.log('e.data.curtrack %d', e.data.curtrack)
    console.log('e.data.playstate %d', e.data.playstate)
    console.log('---')
    console.log(player.playing)
  })
}

Answer 1

Just confirmed it to be a Spotify client bug directly from the dev team on irc.
This is a fix + other candies like a common event interface.

https://gist.github.com/bc1a7e1c06c1077f238d (Emitter comes from the component repo https://github.com/component/emitter)

Using my patch we can do something like this:

var sp = getSpotifyApi(1)
var models = sp.require('sp://import/scripts/api/models')
var player = sp.require('player-fix').player

window.onload = function init() {
  console.log('subscribing')

  player.on('play', function () {
    console.log('play')
  }).on('pause', function () {
    console.log('pause')
  }).on('trackChange', function (track) {
    console.log('trackChange', track.data.name)
  }).on('shuffleChange', function (shuffle) {
    console.log('shuffleChange', shuffle)
  }).on('repeatChange', function (repeat) {
    console.log('repeatChange', repeat)
  }).on('volumeChange', function (volume) {
    console.log('volumeChange', volume)
  }).on('contextChange', function () {
    console.log('contextChange')
  })
}