Javascript-函数外部的数组长度

Question

I would like to know how can I use array.length outside of a function so I can work with that value elsewhere. I have this script:

var length = url_ytb.length; //returns 2

function onPlayerStateChange(event) {      
    if(event.data === 0) { 
        array_position++;
        player.loadVideoById(url_ytb[array_position]);
        length--;
    }
}

if (length == 0) {
  alert("Good");
}

My problem is that the alert won't happen. I have printed the length variable but it still returns 2 when it should return 0.

Answer 1

No. You can't as you are checking before the event itself. You have to check it when the event occurs. So it should be

function onPlayerStateChange(event) {      
    if(event.data === 0) { 
        array_position++;
        player.loadVideoById(url_ytb[array_position]);
        length--;
    }
   if (length == 0) {
     alert("Good");
   }
}