Javascript Blogger Recent Posts控制台错误：无法读取属性'；标题'；未定义的

我发现这个最近的博客脚本将显示某个标签或标签的最新帖子。剧本写得很好。但是，如果我多次使用此脚本来显示不同标签的最近帖子，并抛出以下错误：

无法读取未定义的属性“title”

查看脚本，我无法找出是什么导致了这种情况，或者如何修复它

<script style='text/javascript'>
    //<![CDATA[
    function labelthumbs(json) {
        document.write('<ul class="label_with_thumbs">');
        for (var i = 0; i < numposts; i++) {
            var entry = json.feed.entry[i];
            var posttitle = entry.title.$t;
            var posturl;
            if (i == json.feed.entry.length) break;
            for (var k = 0; k < entry.link.length; k++) {
                if (entry.link[k].rel == 'replies' && entry.link[k].type == 'text/html') {
                    var commenttext = entry.link[k].title;
                    var commenturl = entry.link[k].href;
                }
                if (entry.link[k].rel == 'alternate') {
                    posturl = entry.link[k].href;
                    break;
                }
            }
            var thumburl;
            try {
                thumburl = entry.media$thumbnail.url;
            } catch (error) {
                s = entry.content.$t;
                a = s.indexOf("<img");
                b = s.indexOf("src=\"", a);
                c = s.indexOf("\"", b + 5);
                d = s.substr(b + 5, c - b - 5);
                if ((a != -1) && (b != -1) && (c != -1) && (d != "")) {
                    thumburl = d;
                } else thumburl = 'http://3.bp.blogspot.com/-O-vjxP03hYo/UXVtH90_iQI/AAAAAAAAAG4/60hz9Rn5FWA/s1600/No+Image+1.gif';
            }
            var postdate = entry.published.$t;
            var cdyear = postdate.substring(0, 4);
            var cdmonth = postdate.substring(5, 7);
            var cdday = postdate.substring(8, 10);
            var monthnames = new Array();
            monthnames[1] = "Jan";
            monthnames[2] = "Feb";
            monthnames[3] = "Mar";
            monthnames[4] = "Apr";
            monthnames[5] = "May";
            monthnames[6] = "June";
            monthnames[7] = "July";
            monthnames[8] = "Aug";
            monthnames[9] = "Sept";
            monthnames[10] = "Oct";
            monthnames[11] = "Nov";
            monthnames[12] = "Dec";
            document.write('<li class="clearfix">');
            if (showpostthumbnails == true) document.write('<a href="' + posturl + '" target ="_top"><img class="label_thumb" src="' + thumburl + '"/></a>');
            document.write('<strong><a href="' + posturl + '" target ="_top">' + posttitle + '</a></strong><br>');
            if ("content" in entry) {
                var postcontent = entry.content.$t;
            } else if ("summary" in entry) {
                var postcontent = entry.summary.$t;
            } else var postcontent = "";
            var re = /<\S[^>]*>/g;
            postcontent = postcontent.replace(re, "");
            if (showpostsummary == true) {
                if (postcontent.length < numchars) {
                    document.write('');
                    document.write(postcontent);
                    document.write('');
                } else {
                    document.write('');
                    postcontent = postcontent.substring(0, numchars);
                    var quoteEnd = postcontent.lastIndexOf(" ");
                    postcontent = postcontent.substring(0, quoteEnd);
                    document.write(postcontent + '...');
                    document.write('');
                }
            }
            var towrite = '';
            var flag = 0;
            document.write('<br>');
            if (showpostdate == true) {
                towrite = towrite + monthnames[parseInt(cdmonth, 10)] + '-' + cdday + ' - ' + cdyear;
                flag = 1;
            }
            if (showcommentnum == true) {
                if (flag == 1) {
                    towrite = towrite + ' | ';
                }
                if (commenttext == '1 Comments') commenttext = '1 Comment';
                if (commenttext == '0 Comments') commenttext = 'No Comments';
                commenttext = '<a href="' + commenturl + '" target ="_top">' + commenttext + '</a>';
                towrite = towrite + commenttext;
                flag = 1;;
            }
            if (displaymore == true) {
                if (flag == 1) towrite = towrite + ' | ';
                towrite = towrite + '<a href="' + posturl + '" class="url" target ="_top">More »</a>';
                flag = 1;;
            }
            document.write(towrite);
            document.write('</li>');
            if (displayseparator == true) if (i != (numposts - 1)) document.write('');
        }
        document.write('</ul>');
    }
    //]]>
</script>
<script type='text/javascript'>
    var numposts = 3;
    var showpostthumbnails = true;
    var displaymore = false;
    var displayseparator = true;
    var showcommentnum = false;
    var showpostdate = false;
    var showpostsummary = true;
    var numchars = 100;
</script>
<script type="text/javascript" src="/feeds/posts/default/-/video?orderby=published&alt=json-in-script&callback=labelthumbs"></script>

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该错误是由

numposts

变量值大于特定标签中存在的帖子数引起的

例如，您的标签可能只包含一篇文章，但如果您提供的

numposts

的值大于1，那么在For循环的第二次迭代中，它将抛出上述错误，因为它们不会是任何要迭代的文章

对于工作演示，请检查，上面代码的两个实例在控制台中工作正常，没有任何错误

---

在第二个演示中，我给了

numposts

一个大于该特定标签中的帖子的值，因此在控制台中，您会发现与您的相同的错误

我认为您没有更改标签名称，因为blogger仅在特定标签下显示了1次相关帖子。但是，您必须尝试更改JS上最后一行的blogger标签：

<script type="text/javascript" src="/feeds/posts/default/-/video?orderby=published&alt=json-in-script&callback=labelthumbs"></script>

---

只需将video标签更改为另一个标签，我相信它会起作用…

很明显，json.feed.entry[I]不包含任何值。因此，条目变量仍然未定义。你需要调试更多！我不同意。该错误仅在脚本被多次使用时发生。如果它不包含任何值，为什么它只使用一次就可以工作呢？这里有太多的未知数让我们无法确定到底出了什么问题。例如，我们不知道什么是

numposts

。不，第一个标签是视频，第二个是照片。

<script type="text/javascript" src="/feeds/posts/default/-/video?orderby=published&alt=json-in-script&callback=labelthumbs"></script>