遍历数组时的错误处理

Question

Newbie here. I've written a simple test function that iterates through a bunch of song listings and for each one tries to fetch the album cover image from the Last.fm API. If it doesn't work, it's supposed to display the track and artist name in the console. When I run it, however, it always displays the same artist/track pair, namely the last one iterated through, not the specific one that triggered the error. I'm not sure what's going on.

$(document).ready(function(){
array = []
for (var item in billboard) {
  var track = billboard[item]['song'];
  var artist = billboard[item]['artist'];
  $.getJSON("http://ws.audioscrobbler.com/2.0/?method=track.getInfo&api_key=myAPIkey&artist=" + artist + "&track=" + track + "&format=json&callback=?", function(data) {
      try{
        image = data.track.album.image[2]['#text'];
      }
      catch (err) {
        console.log(track + " - " artist);
        }
      });
    }
});


 var billboard = {

 "7-12-1986": {"artist": "Simply Red", "song": "Holding Back The Years"},
"6-28-1986": {"artist": "Patti LaBelle ", "song": "On My Own"},
 "7-5-1986": {"artist": "Billy Ocean", "song": "There'll Be Sad Songs (To Make You Cry)"},
 .....
 }

Answer 1

Have a look at the difference between for and for in

I think in this case you should use a standard for loop.