Mixcloud

"mixcloud.com": {
    "play": function(){
      document.querySelector('.player-control').click();
      return 'play';
    },
    "pause": function(){
      document.querySelector('.player-control').click();
      return 'pause';
    },
    "is_playing": function(){
      return document
            .querySelector('.player-control')
            .classList
            .contains('pause-state');
    }
  }

Soundcloud

  "soundcloud.com": {
    "play": function(){
      document.querySelector('.playControl').click();
      return 'play';
    },
    "pause": function(){
      document.querySelector('.playControl').click();
      return 'pause';
    },
    "next": function(){
      document.querySelector('.skipControl__next').click();
    },
    "prev": function(){
      document.querySelector('.skipControl__previous').click();
    },
    "is_playing": function(){
      return document.querySelector('.playControl').classList.contains('playing');
    }
  }