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javascript之如何使用 Greasemonkey 调用现有视频的 Youtube-Flash-API

2024年02月27日9freeliver54

我想编写一个 Greasemonkey 脚本来检测网站上的 YouTube 视频何时开始播放,以停止我的 winamp 播放音乐。一切正常,我的脚本检测视频,启用 API,并且 onYouTubePlayerReady 事件被调用。但我不知道如何注册 onStateChange 回调,这是我的代码:

unsafeWindow.onYouTubePlayerReady = function (playerId) 
{ 
    alert('Visible'); 
 
    document.getElementById(playerId).addEventListener('onStateChange', 'stateChanged');     
 
    alert('Not visible, so the line above crashes'); 
} 
 
unsafeWindow.stateChanged = function (state) 
{ 
    alert('never called, too'); 
} 

这个问题有解决办法还是根本不可能?

请您参考如下方法:

"the problem is just the listener on "onStateChange" "

好吧,为了解决一些范围界定问题,最好只注入(inject)与 YouTube API 交互的代码。

以下内容适用于 Firefox+Greasemonkey、Chrome 或 Chrome+Tampermonkey。它也应该适用于任何支持用户脚本的浏览器:

function GM_main () { 
    window.stateChanged = function (state) { 
        console.log ('GM: In stateChanged().  State = ', state); 
    } 
 
    window.onYouTubePlayerReady = function (playerId) { 
        /*-- playerId is not being set by Youtube. Use 
            hard-coded id (movie_player) instead. 
        */ 
        var playerNode  = document.getElementById ("movie_player"); 
        if (playerNode) { 
            /*--- Note, inside onYouTubePlayerReady ONLY, the YouTube API 
                seems to override addEventListener. Hence the nonstandard 
                parameters. 
            */ 
            playerNode.addEventListener ('onStateChange', 'stateChanged'); 
 
            console.log ('GM: Listener installed just fine.'); 
        } 
        else 
            console.error ("GM: Player node not found!"); 
    } 
} 
 
addJS_Node (null, null, GM_main); 
 
function addJS_Node (text, s_URL, funcToRun, runOnLoad) { 
    var D                                   = document; 
    var scriptNode                          = D.createElement ('script'); 
    if (runOnLoad) { 
        scriptNode.addEventListener ("load", runOnLoad, false); 
    } 
    scriptNode.type                         = "text/javascript"; 
    if (text)       scriptNode.textContent  = text; 
    if (s_URL)      scriptNode.src          = s_URL; 
    if (funcToRun)  scriptNode.textContent  = '(' + funcToRun.toString() + ')()'; 
 
    var targ = D.getElementsByTagName ('head')[0] || D.body || D.documentElement; 
    targ.appendChild (scriptNode); 
}