引用错误:未定义YouTube/YouTube API

Question

我有以下代码，试图用YouTube Data API进行搜索。我正在使用express generated stack和jade。

#player
    script.
        // 2. This code loads the IFrame Player API code asynchronously.
        var tag = document.createElement('script');
        tag.src = "https://www.youtube.com/iframe_api";
        var firstScriptTag = document.getElementsByTagName('script')[0];
        firstScriptTag.parentNode.insertBefore(tag, firstScriptTag);
        // 3. This function creates an <iframe> (and YouTube player)
        //    after the API code downloads.
        var player;
        function onYouTubeIframeAPIReady() {
            player = new YT.Player('player', {
                height: '345',
                width: '540',
                videoId: 'M7lc1UVf-VE',
                events: {
                    'onReady': onPlayerReady,
                    'onStateChange': onPlayerStateChange
                }
            });
        }
        // 4. The API will call this function when the video player is ready.
        function onPlayerReady(event) {
            event.target.playVideo();
        }
        // 5. The API calls this function when the player's state changes.
        //    The function indicates that when playing a video (state=1),
        //    the player should play for six seconds and then stop.
        var done = false;
        function onPlayerStateChange(event) {
            if (event.data == YT.PlayerState.PLAYING && !done) {
                setTimeout(stopVideo, 6000);
                done = true;
            }
        }
        function stopVideo() {
            player.stopVideo();
        }
        function googleApiClientReady() {
            gapi.client.setApiKey('AIzaSyCgOmTzCI4-gkUhL4hOm9R6I9tmUlVqtCw');
            gapi.client.load('youtube', 'v3', function() {
                /**
                * This function searches for videos related to the keyword 'dogs'. The video IDs and titles
                * of the search results are logged to Apps Script's log.
                *
                * Note that this sample limits the results to 25. To return more results, pass
                * additional parameters as documented here:
                *   https://developers.google.com/youtube/v3/docs/search/list
                */
                function searchByKeyword() {
                    var results = YouTube.Search.list('id,snippet', {q: 'dogs', maxResults: 25});
                    for(var i in results.items) {
                        var item = results.items[i];
                        console.log('[%s] Title: %s', item.id.videoId, item.snippet.title);
                    }
                }
                searchByKeyword();
            });
        }
    script(src="https://apis.google.com/js/client.js?onload=googleApiClientReady")`

根据我的代码，我认为它应该加载一个视频（它确实加载了），然后搜索"狗"，并将结果记录到控制台。

然而，我收到错误：

ReferenceError: YouTube is not defined

我不知道我做错了什么。。。脚本没有加载的东西可能。。。但我想，我已经试着在所有可能的地方加载脚本了。

谢谢。

更新

我再次将script(放在底部——就像在我的原始代码中一样。。。现在我可以确认searchByKeyword方法正在运行。。。但是问题又回到了CCD_ 7问题。在下面的块中，第一行来自我在searchByKeyword方法开头放的console.log消息，第二行是相同的错误（这篇文章的标题）：

searchByKeyword is running ReferenceError: YouTube is not defined

Answer 1

您最初的问题是，当gapi.client加载时，它扩展了基本gapi对象。要访问Youtube api，请使用gapi.client.youtube.search而不是Youtube.Search。

此外，Javascript本质上是异步的，因此任何XHR请求的返回都必须在回调或promised中。

function searchByKeyword() {
  var request = gapi.client.youtube.search.list({
    q: 'dogs',
    part: 'snippet'
  });
  request.execute(function(results) {
    for(var i in results.items) {
      var item = results.items[i];
      console.log('[%s] Title: %s', item.id.videoId,item.snippet.title);
    }
  });
 }
}