它的工作方式是
我试图从json中获取标题和url，而当我点击“convert”按钮时，我得到 - Uncaught TypeError：无法读取未定义的属性'length'
链接到 jsFiddle
这是html和js
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<meta http-equiv="Content-Language" content="he" /> <title>JSON Sample</title>
</head>
<body>
<textarea id="jsonvalue" style="width:100%" rows="1"></textarea>
<button id="convert">Click here to convert!</button>
<div id="placeholder"></div>
<script src="http://code.jquery.com/jquery-1.9.1.min.js"></script>
<script>
$(document).ready(function () {
$("#convert").click(function () {
var output = '<!DOCTYPE html><html><head><meta http-equiv="Content-Type" content="text/html;
charset=UTF-8" /><title>Instapaper: Export</title></head><body><h1>Unread</h1><ol></ol><h1>Archive</h1><ol>';
var data = $('#jsonvalue').val();
$.each(data.items, function (i, items) {
output += '<li><a href="' + items.alternate[0].href + '">' + items.title + '</li>';
});
output += '</ol></body></html>';
$('#placeholder').text(output);
});
});
</script>
</body>
</html>
这是我在textarea中粘贴的json
{
"id" : "user/17115776656148603551/state/com.google/starred",
"title" : "Dasa סימן פריטים בכוכב ב-Google Reader",
"author" : "Dasa",
"updated" : 1368699933,
"direction" : "ltr",
"items" : [ {
"crawlTimeMsec" : "1368699933957",
"timestampUsec" : "1368699933957939",
"id" : "tag:google.com,2005:reader/item/eb307953496c3755",
"categories" : [ "user/17115776656148603551/state/com.google/starred", "user/17115776656148603551/state/com.google/fresh", "search", "job search", "news stories", "trending", "job hunting", "news", "vanity searches", "productivity", "search query", "google alerts", "alerts", "organization", "local news", "google", "time savers", "trending news", "shortcuts", "notifications" ],
"title" : "Five Creative Uses for Google Alerts",
"published" : 1366282800,
"updated" : 1366282800,
"canonical" : [ {
"href" : "http://lifehacker.com/five-creative-uses-for-google-alerts-475278626"
} ],
"alternate" : [ {
"href" : "http://feeds.gawker.com/~r/lifehacker/full/~3/jaLbxODg6SM/five-creative-uses-for-google-alerts-475278626",
"type" : "text/html"
} ],
"summary" : {
"direction" : "ltr",
"content" : "<p><img height=\"360\" width=\"640\" src=\"http://img.gawkerassets.com/img/18kye9icys64djpg/ku-xlarge.jpg\"></p><p>Google Alerts is one of Google's hidden gems. It's a really powerful tool to keep track of trends, interesting topics, or anything really new that appears on the web. If you're not using it already, here are a few creative ways to get started with it.</p><p><a href=\"http://lifehacker.com/five-creative-uses-for-google-alerts-475278626\">Read more...</a></p><img width=\"1\" height=\"1\" src=\"http://lifehacker.feedsportal.com/c/34977/f/647165/s/2add7ec3/mf.gif\" border=\"0\"><div><table border=\"0\"><tr><td valign=\"middle\"><a href=\"http://share.feedsportal.com/share/twitter/?u=http%3A%2F%2Flifehacker.com%2Ffive-creative-uses-for-google-alerts-475278626&t=Five+Creative+Uses+for+Google+Alerts\"><img src=\"http://res3.feedsportal.com/social/twitter.png\" border=\"0\"></a> <a href=\"http://share.feedsportal.com/share/facebook/?u=http%3A%2F%2Flifehacker.com%2Ffive-creative-uses-for-google-alerts-475278626&t=Five+Creative+Uses+for+Google+Alerts\"><img src=\"http://res3.feedsportal.com/social/facebook.png\" border=\"0\"></a> <a href=\"http://share.feedsportal.com/share/linkedin/?u=http%3A%2F%2Flifehacker.com%2Ffive-creative-uses-for-google-alerts-475278626&t=Five+Creative+Uses+for+Google+Alerts\"><img src=\"http://res3.feedsportal.com/social/linkedin.png\" border=\"0\"></a> <a href=\"http://share.feedsportal.com/share/gplus/?u=http%3A%2F%2Flifehacker.com%2Ffive-creative-uses-for-google-alerts-475278626&t=Five+Creative+Uses+for+Google+Alerts\"><img src=\"http://res3.feedsportal.com/social/googleplus.png\" border=\"0\"></a> <a href=\"http://share.feedsportal.com/share/email/?u=http%3A%2F%2Flifehacker.com%2Ffive-creative-uses-for-google-alerts-475278626&t=Five+Creative+Uses+for+Google+Alerts\"><img src=\"http://res3.feedsportal.com/social/email.png\" border=\"0\"></a></td></tr></table></div><br><br><a href=\"http://da.feedsportal.com/r/163644809562/u/49/f/647165/c/34977/s/2add7ec3/kg/342/a2.htm\"><img src=\"http://da.feedsportal.com/r/163644809562/u/49/f/647165/c/34977/s/2add7ec3/kg/342/a2.img\" border=\"0\"></a><img width=\"1\" height=\"1\" src=\"http://pi.feedsportal.com/r/163644809562/u/49/f/647165/c/34977/s/2add7ec3/kg/342/a2t.img\" border=\"0\"><img src=\"http://feeds.feedburner.com/~r/lifehacker/full/~4/jaLbxODg6SM\" height=\"1\" width=\"1\">"
},
"author" : "Alan Henry",
"comments" : [ ],
"annotations" : [ ],
"origin" : {
"streamId" : "feed/http://lifehacker.com/index.xml",
"title" : "Lifehacker",
"htmlUrl" : "http://lifehacker.com"
}
}, {
"crawlTimeMsec" : "1368699816215",
"timestampUsec" : "1368699816215241",
"id" : "tag:google.com,2005:reader/item/84c25c636b707078",
"categories" : [ "user/17115776656148603551/state/com.google/read", "user/17115776656148603551/state/com.google/starred", "user/17115776656148603551/state/com.google/fresh", "Breakfast", "Gluten-Free", "Photo", "Pudding" ],
"title" : "yogurt panna cotta with walnuts and honey",
"published" : 1366988860,
"updated" : 1366988860,
"canonical" : [ {
"href" : "http://smittenkitchen.com/blog/2013/04/yogurt-panna-cotta-with-walnuts-and-honey/"
} ],
"alternate" : [ {
"href" : "http://feedproxy.google.com/~r/smittenkitchen/~3/t_w8asbkyNg/",
"type" : "text/html"
} ],
"content" : {
"direction" : "ltr",
"content" : "<p><a href=\"http://smittenkitchen.com/blog/2013/04/yogurt-panna-cotta-with-walnuts-and-honey/\" title=\"yogurt panna cotta with walnuts and honey\"><img src=\"http://farm9.staticflickr.com/8400/8682467912_efaa762c89.jpg\" width=\"500\" height=\"333\" alt=\"yogurt panna cotta with walnuts and honey\"></a></p>\nGuys, I just discovered the ultimate weekend brunch treat/decadent dessert that still contains a whiff of moderation/<a href=\"http://www.flickr.com/photos/smitten/8681658077/in/photostream\">preschooler</a> snack. The ingredient list is so short, and the cooking process is so simple that you’ll have the recipe memorized by the time you make it the second time. And you will make it a second time, maybe even within a week. It looks pretty, tastes luxurious and… well, most of you probably discovered panna cotta a decade ago.\n<p><a href=\"http://www.flickr.com/photos/smitten/8682466230/\" title=\"lemon, gelatin, sugar, milk/cream, yogurt\"><img src=\"http://farm9.staticflickr.com/8395/8682466230_9e19d63848.jpg\" width=\"500\" height=\"333\" alt=\"lemon, gelatin, sugar, milk/cream, yogurt\"></a><br>\n<a href=\"http://www.flickr.com/photos/smitten/8682466352/\" title=\"thick greek yogurt\"><img src=\"http://farm9.staticflickr.com/8262/8682466352_5a3120eb08.jpg\" width=\"500\" height=\"333\" alt=\"thick greek yogurt\"></a></p>\n<p>I’m sorry, I’m just slow. For example, this week I started reading <a href=\"http://rads.stackoverflow.com/amzn/click/1594483299">this new book</a> that everyone was talking about in September … 2007. And that’s just the beginning. Gallery wall? Skinny jeans? Arrested Development? Quinoa? People, I am <i>on it</i>. True to sluggish form, it’s been a full four years since my friend Nicole gushed to me about the wonders of yogurt panna cotta. I put it on my cooking to-do list, blinked, and that about brings us up to last week when I saw it on my list and thought, “right, wasn’t I going to make that a few days ago?”</p>\n<p><a href=\"http://www.flickr.com/photos/smitten/8681355169/\" title=\"yogurt whisked with milk or cream\"><img src=\"http://farm9.staticflickr.com/8522/8681355169_9657d4a377.jpg\" width=\"500\" height=\"333\" alt=\"yogurt whisked with milk or cream\"></a></p>\n<p><b>... Read the rest of <a href=\"http://smittenkitchen.com/blog/2013/04/yogurt-panna-cotta-with-walnuts-and-honey/\">yogurt panna cotta with walnuts and honey</a> on <a href=\"http://smittenkitchen.com\">smittenkitchen.com</a></b></p>\n<hr>\n<p><small>© smitten kitchen 2006-2012. |\n<a href=\"http://smittenkitchen.com/blog/2013/04/yogurt-panna-cotta-with-walnuts-and-honey/\">permalink to <b>yogurt panna cotta with walnuts and honey</b></a> | <a href=\"http://smittenkitchen.com/blog/2013/04/yogurt-panna-cotta-with-walnuts-and-honey/#comments\">220 comments</a> to date | see more: <a href=\"http://smittenkitchen.com/blog/category/breakfast/\" title=\"View all posts in Breakfast\" rel=\"category tag\">Breakfast</a>, <a href=\"http://smittenkitchen.com/blog/category/gluten-free/\" title=\"View all posts in Gluten-Free\" rel=\"category tag\">Gluten-Free</a>, <a href=\"http://smittenkitchen.com/blog/category/photo/\" title=\"View all posts in Photo\" rel=\"category tag\">Photo</a>, <a href=\"http://smittenkitchen.com/blog/category/pudding/\" title=\"View all posts in Pudding\" rel=\"category tag\">Pudding</a>\n</small></p>"
},
"author" : "deb",
"comments" : [ ],
"annotations" : [ ],
"origin" : {
"streamId" : "feed/http://feeds.feedburner.com/smittenkitchen",
"title" : "smitten kitchen",
"htmlUrl" : "http://smittenkitchen.com"
}
} ]
}
答案 0 :(得分：2)
您尝试迭代data.items，这将为null，因为data是一个没有items属性的字符串。您需要首先使用JSON.parse解析JSON对象。
另一个问题是，现在你的JSON不会解析，因为它无效。您尚未正确转义content.content中的所有引号。
之后，如果您想更改标记而不插入可读代码，则需要使用.html而不是.text设置输出。
This revised fiddle将起作用。您缺少一个转义字符，用于结尾带有“this new book”文本的链接href属性的引号。
答案 1 :(得分：0)
尝试这样的事情
$(document).ready(function () {
$("#convert").click(function () {
var output = '<!DOCTYPE html><html><head><meta http-equiv="Content-Type" content="text/html" charset="UTF-8" /><title>Instapaper: Export</title></head><body><h1>Unread</h1><ol></ol><h1>Archive</h1><ol>';
var data = $('#jsonvalue').val();
data = jQuery.parseJSON(data);
$.each(data.items, function (i, items) {
output += '<li><a href="' + items.alternate[0].href + '">' + items.title + '</li>';
});
output += '</ol></body></html>';
$('#placeholder').text(output);
});
});