chrome/test/data/extensions/subscribe_page_action/feed_finder.js

   1 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 // First check to see if this document is a feed. If so, it will redirect.
   6 // Otherwise, check if it has embedded feed links, such as:
   7 // (<link rel="alternate" type="application/rss+xml" etc). If so, show the
   8 // page action icon.
   9
  10 debugMsg(logLevels.info, "Running feed finder script");
  11
  12 if (!isFeedDocument()) {
  13   debugMsg(logLevels.info, "Document is not a feed, check for <link> tags.");
  14   findFeedLinks();
  15 }
  16
  17 // See if the document contains a <link> tag within the <head> and
  18 // whether that points to an RSS feed.
  19 function findFeedLinks() {
  20   // Find all the RSS link elements.
  21   var result = document.evaluate(
  22       '//*[local-name()="link"][contains(@rel, "alternate")] ' +
  23       '[contains(@type, "rss") or contains(@type, "atom") or ' +
  24       'contains(@type, "rdf")]', document, null, 0, null);
  25
  26   var feeds = [];
  27   var item;
  28   var count = 0;
  29   while (item = result.iterateNext()) {
  30     feeds.push({"href": item.href, "title": item.title});
  31     ++count;
  32   }
  33
  34   if (count > 0) {
  35     // Notify the extension needs to show the RSS page action icon.
  36     chrome.extension.sendMessage({msg: "feedIcon", feeds: feeds});
  37   }
  38 }
  39
  40 // Check to see if the current document is a feed delivered as plain text,
  41 // which Chrome does for some mime types, or a feed wrapped in an html.
  42 function isFeedDocument() {
  43   var body = document.body;
  44
  45   debugMsg(logLevels.info, "Checking if document is feed");
  46
  47   var soleTagInBody = "";
  48   if (body && body.childElementCount == 1) {
  49     soleTagInBody = body.children[0].tagName;
  50     debugMsg(logLevels.info, "The sole tag in the body is: " + soleTagInBody);
  51   }
  52
  53   // Some feeds show up as feed tags within the BODY tag, for example some
  54   // ComputerWorld feeds. We cannot check for this at document_start since
  55   // the body tag hasn't been defined at that time (contains only HTML element
  56   // with no children).
  57   if (soleTagInBody == "RSS" || soleTagInBody == "FEED" ||
  58       soleTagInBody == "RDF") {
  59     debugMsg(logLevels.info, "Found feed: Tag is: " + soleTagInBody);
  60     chrome.extension.sendMessage({msg: "feedDocument", href: location.href});
  61     return true;
  62   }
  63
  64   // Chrome renders some content types like application/rss+xml and
  65   // application/atom+xml as text/plain, resulting in a body tag with one
  66   // PRE child containing the XML. So, we attempt to parse it as XML and look
  67   // for RSS tags within.
  68   if (soleTagInBody == "PRE") {
  69     debugMsg(logLevels.info, "Found feed: Wrapped in PRE");
  70     var domParser = new DOMParser();
  71     var doc = domParser.parseFromString(body.textContent, "text/xml");
  72
  73     if (currentLogLevel >= logLevels.error) {
  74       var error = doc.getElementsByTagName("parsererror");
  75       if (error.length)
  76         debugMsg(logLevels.error, 'error: ' + doc.childNodes[0].outerHTML);
  77     }
  78
  79     // |doc| now contains the parsed document within the PRE tag.
  80     if (containsFeed(doc)) {
  81       // Let the extension know that we should show the subscribe page.
  82       chrome.extension.sendMessage({msg: "feedDocument", href: location.href});
  83       return true;
  84     }
  85   }
  86
  87   debugMsg(logLevels.info, "Exiting: feed is not a feed document");
  88
  89   return false;
  90 }