如何判断当前浏览器是否支持html5的video标签

//检测是否支持HTML5
function checkVideo() {
  if(!!document.createElement(‘video‘).canPlayType){
    var vidTest = document.createElement("video");
    oggTest = vidTest.canPlayType(‘video/ogg; codecs="theora, vorbis"‘);
    if(!oggTest){
      h264Test = vidTest.canPlayType(‘video/mp4; codecs="avc1.42E01E, mp4a.40.2"‘);
      if(!h264Test){
        return false;
      }
      else{
        if(h264Test == "probably"){
          return true;
        }
        else {
          return false;
        }
      }
    }
    else{
      if(oggTest == "probably"){
        return true;
      }
      else{
        return false;
      }
    }
  }
  else{
    return false;
  }
}