Question

function getElsByClass(searchClass,node) {
        if ( node == null )
          node = document;
        var classElements = [],
            els = node.getElementsByTagName("div"),
            elsLen = els.length,
            pattern = new RegExp("(^|\\s)"+searchClass+"(\\s|$)"), i, j;

        for (i = 0, j = 0; i < elsLen; i++) {
          if ( pattern.test(els[i].className) ) {
              classElements[j] = els[i];
              j++;
          }
        }
        return classElements;
    }

function getSong() {
    console.log("getSong ran");
    var songN = getElsByClass("info")[0], nmSong = getCookie();
    console.log(songN);
    songN = songN.getElementsByTagName("a");
    songN = songN[0].innerText + " - " + songN[1].innerText;
    if (nmSong != songN) {
        setCookie(songN);
    } else {
        setCookie(songN);
    }
    sendSong(songN);
    return songN;
}
setInterval(getSong(), 10000);

我已经尝试了songN = document.getElemenetsByClassName("info")，我找到的每一个组合，它只会在关闭前运行30秒，我需要它运行几个小时，无人看管......

我可以跑

var songN = getElsByClass("info")[0];
console.log(songN); //is actually defined when ran in Javascript Console in Chrome..
songN = songN.getElementsByTagName("a");
songN = songN[0].innerText + " - " + songN[1].innerText;

在Javascript控制台中，它准确地返回，我正在尝试做什么，但如果它作为用户脚本运行或者在它被注入网页之后，我得到Uncaught TypeError: Cannot read property 'getElementsByTagName' of undefined，我已经尝试过了通过搜索google和stackoverflow找到了很多不同的方法，我在<head>的window.load上运行了脚本，并试图让它在<body>中运行。

getElsByClass()是我最后一次尝试它，它实际上并不是我的脚本的一部分，只是我尝试从另一个脚本，尝试缩短名称，以便它不会发生冲突，但仍然没有。

===更新===

以下是一些代码..

function getCookie() {
    console.log("getCookie ran");
    var sname = "songname=", ca = document.cookie.split(';'), i = 0, c, t;
    for (i; i < ca.length; i++) {
        c = ca[i].trim();
        if (c.indexOf(sname) == 0) {
            t = c.substring(sname.length, c.length);
            console.log(t);
            return t;
        }
    }
    return "";
}

function setCookie(cvalue) {
    console.log("setCookie ran");
    var d = new Date();
    d.setTime(d.getTime() + 210000);//set it to expire in 3 minutes and 30 seconds from current time (this is average song time.)
    document.cookie = "songname=" + cvalue + "; expires=" + d.toGMTString();
}

任何类型的getElement（s）By ----函数用于按名称获取类，返回undefined

0 个答案: