How to get a youtube playlist using javascript API and json

Question

This is part of my youtube project. I try to extract video information from JSON format but I have problem in this line:

var videoId = data.feed.entry[i].link[1].href;

When I do this in single line not in cikle evrithing is ok but in cikle for or while I have error.

//get youtube ID

function extract(url){
    pos1=url.indexOf("videos/");
    pos2=url.substr(42,11);
    return pos2;
}

//My playlist LINK
var url2="http://gdata.youtube.com/feeds/api/playlists/B2A4E1367126848D?v=2&alt=json";
function playlistinfo(url1) {
    $.ajax({
        url: url1,
        dataType: "jsonp",
        success: function (data) { parseresults(data); }
    });
}

//whit this get playlist data
function parseresults(data) {

    //return playlist clip number
    var klipove= data.feed.openSearch$totalResults.$t;
    //put clips in  <li>

    for(i=0;i<=klipove-1;i++) {
        var videoId = data.feed.entry[i].link[1].href;
        //get video id  ID
        var id= extract(videoId);
        thumb = data.feed.entry[i].media$group.media$thumbnail[0].url;
        $('<li><img src="'+thumb+'" alt="'+id+'" class="thumb"/></li>').appendTo('.cont');
    }
}

Answer 1

IMHO, you code can be much shortened if you use $.getJSON, $.each
Try this.

var playListURL = 'http://gdata.youtube.com/feeds/api/playlists/B2A4E1367126848D?v=2&alt=json&callback=?';
var videoURL= 'http://www.youtube.com/watch?v=';
$.getJSON(playListURL, function(data) {
    var list_data="";
    $.each(data.feed.entry, function(i, item) {
        var feedTitle = item.title.$t;
        var feedURL = item.link[1].href;
        var fragments = feedURL.split("/");
        var videoID = fragments[fragments.length - 2];
        var url = videoURL + videoID;
        var thumb = "http://img.youtube.com/vi/"+ videoID +"/default.jpg";
        if (videoID !='videos') {
list_data += '<li><a href="'+ url +'" title="'+ feedTitle +'"><img alt="'+ feedTitle+'" src="'+ thumb +'"</a></li>';
}
    });
    $(list_data).appendTo(".cont");
});

Demo: Fiddle for the playlist you have provided

P.S: Keep in mind that thumbnail for a youtube video could be found at

http://img.youtube.com/vi/{video-id}/default.jpg 

( More Info here )