Microscopic Javascript fullscreen controller

fullscreen_controller.js

  // Fullscreen controller used on www.windy.com
  const d = document
  , el = $('#fullscreen')
  , isFullscreen = () => d.fullscreen || d.webkitIsFullScreen || d.mozFullScreen
  , onFullChange = () =>	el.innerHTML = isFullscreen() ? '' : '-' // Change of icon 

  d.addEventListener('fullscreenchange', onFullChange )
  d.addEventListener('webkitfullscreenchange',onFullChange )
  d.addEventListener('webkitfullscreenchange',onFullChange )
  d.addEventListener('mozfullscreenchange',onFullChange )
  d.addEventListener('MSFullscreenChange',onFullChange )

  el.onclick = toggleFullscreen

  function toggleFullscreen() {
    var elem = document.body

    if( isFullscreen() ) {

      if( d.exitFullscreen) d.exitFullscreen() 
      else if( d.webkitExitFullscreen) d.webkitExitFullscreen() 
      else if( d.webkitCancelFullScreen) d.webkitCancelFullScreen() 
      else if( d.mozCancelFullScreen) d.mozCancelFullScreen() 
      else if( d.msExitFullscreen) d.msExitFullscreen() 

    } else {

      if (elem.requestFullscreen) elem.requestFullscreen();
      else if (elem.msRequestFullscreen) elem.msRequestFullscreen();
      else if (elem.mozRequestFullScreen) elem.mozRequestFullScreen();
      else if (elem.webkitRequestFullscreen) elem.webkitRequestFullscreen();
    }
  }