Get the current value of a function which returns random values

问题

The thing I am trying to do is to get the current video Id of the youtube videos that are currently playing and display it in a div.

This is my YT iframe API code (like in the basic example on the google dev site):

  var player;
  function onYouTubeIframeAPIReady() {
    player = new YT.Player('player', {
      height: '390',
      width: '640',
      videoId: currentVideoId,
      events: {
        'onReady': onPlayerReady,
        'onStateChange': onPlayerStateChange,
        'onError': onError,
      },

    });
  }

as you can see, the VideoId (the first video it will play) is set by a variable called "currentVideoId", which was set before like this:

var currentVideoId = '9z4Kft47kBM'

I want to display the current ID in a div

<div id="currentVideoDiv"></div>

To do this i used this code:

$('#currentVideoDiv').html('Currently Playing:' + currentVideoId);

so far so good, it shows my first videoID correctly.

Now after the first video has ended, the onStateChange event will call this function:

function onPlayerStateChange(event) {
 if(event.data === 0) {             
     swapVideo();      
        }
  }

The "swapVideo" function will call the function getId();

 function swapVideo() {   

 player.stopVideo();
 player.loadVideoById(getId()); 
 }

The getId() function will get a random videoID from an xml file, don´t worry about that in detail.

 function getId() {
 return videos[Math.floor(Math.random() * videos.length)];


}

So now a new video with a new videoId is playing, but the value in the currentVideoDiv is still the same since nothing did change it.

The question is, how can i get the new current id, which was set randomly by the getId function and display it in the currentVideoDiv?

回答1:

This is based on the assumption that you update the display id after loadVideoById

function swapVideo() {

 var currentVideoId = getId();

 player.stopVideo();
 player.loadVideoById(currentVideoId); 

 $('#currentVideoDiv').html('Currently Playing:' + currentVideoId);

}

来源：https://stackoverflow.com/questions/20274897/get-the-current-value-of-a-function-which-returns-random-values