jquery - 如何通过Jquery获取页面打开图元数据

Question

用户可以将 URL 粘贴到我网站上的文本框中。当他们这样做时，我想通过 jQuery AJAX 获取该 URL 并从中读取 opengraph 元数据。我怎样才能做到这一点？

我读了这篇文章How to read Open Graph and meta tags from a webpage with a url但其中的链接已损坏，并且它比我需要的更高级，而不是在 jQuery 中:)

除了 opengraph 元数据之外，我不需要任何其他东西，因此不需要解析结构等。

以下是页面示例:http://www.ebay.com/itm/Microsoft-Surface-Pro-3-12-Tablet-256GB-SSD-Intel-Core-i7-Haswell-8GB-RAM-/281656969697

所以我想提取的字段之一是 <meta property="og:image" content="http://i.ebayimg.com/images/i/281656969697-0-1/s-l1000.jpg" ></meta> ，准确地说是值 http://i.ebayimg.com/images/i/281656969697-0-1/s-l1000.jpg

我现在拥有的内容是从这里复制的:http://icant.co.uk/articles/crossdomain-ajax-with-jquery/error-handling.html

请参阅我标记为 @Flo 的评论，我想在其中提取开放图数据，但我不知道如何解析 JSON 响应。

<a href="www.ebay.com/itm/Microsoft-Surface-Pro-3-12-Tablet-256GB-SSD-Intel-Core-i7-Haswell-8GB-RAM-/281656969697" class="ajaxtrigger">Load Ajax Content</a>
<div id="target"></div>

    <script language="javascript" type="text/javascript">
    $(function () {

        $('.ajaxtrigger').click(function () {
            var container = $('#target');
            container.attr('tabIndex', '-1');
            var trigger = $(this);
            var url = trigger.attr('href');
            if (!trigger.hasClass('loaded')) {
                trigger.append('<span></span>');
                trigger.addClass('loaded');
                var msg = trigger.find('span').last();
            } else {
                var msg = trigger.find('span').last();
            }
            doAjax(url, msg, container);
            return false;
        });
    });


    function doAjax(url, msg, container) {
        // if the URL starts with http
        if (url.match('^http')) {
            // assemble the YQL call
            msg.removeClass('error');
            msg.html(' (loading...)');
            $.getJSON("//query.yahooapis.com/v1/public/yql?" +
                      "q=SELECT%20*%20FROM%20html%20WHERE%20url=%27" +
                      encodeURIComponent(url) +
                      "%27%20AND%20xpath=%27descendant-or-self::meta%27&format=json&callback=?",
              function (data) {
                  if (data.results[0]) {
                      var data = filterData(data.results[0]);

                      //@Flo: get metadata from result, but now???

                      msg.html(' (ready.)');
                      container.
                        html(data).
                          focus().
                            effect("highlight", {}, 1000);
                  } else {
                      msg.html(' (error!)');
                      msg.addClass('error');
                      var errormsg = '<p>Error: could not load the page.</p>';
                      container.
                        html(errormsg).
                          focus().
                            effect('highlight', { color: '#c00' }, 1000);
                  }
              }
            );
        } else {
            $.ajax({
                url: url,
                timeout: 5000,
                success: function (data) {
                    msg.html(' (ready.)');
                    container.
                      html(data).
                        focus().
                          effect("highlight", {}, 1000);
                },
                error: function (req, error) {
                    msg.html(' (error!)');
                    msg.addClass('error');
                    if (error === 'error') { error = req.statusText; }
                    var errormsg = 'There was a communication error: ' + error;
                    container.
                      html(errormsg).
                        focus().
                          effect('highlight', { color: '#c00' }, 1000);
                },
                beforeSend: function (data) {
                    msg.removeClass('error');
                    msg.html(' (loading...)');
                }
            });
        }
    }
    function filterData(data) {
        // filter all the nasties out
        // no body tags
        data = data.replace(/<?\/body[^>]*>/g, '');
        // no linebreaks
        data = data.replace(/[\r|\n]+/g, '');
        // no comments
        data = data.replace(/<--[\S\s]*?-->/g, '');
        // no noscript blocks
        data = data.replace(/<noscript[^>]*>[\S\s]*?<\/noscript>/g, '');
        // no script blocks
        data = data.replace(/<script[^>]*>[\S\s]*?<\/script>/g, '');
        // no self closing scripts
        data = data.replace(/<script.*\/>/, '');
        // [... add as needed ...]
        return data;
    }


    </script>

该查询返回的对象是:

Object {query: Object}
query: Object
count: 33
created: "2015-05-02T04:36:46Z"
lang: "en-US"
results: Object
meta: Array[33]
0: Object
name: "viewport"
__proto__: Object
1: Object
content: "main"
name: "layout"
__proto__: Object

如何过滤此响应以返回 og:image值？

Answer 1

尝试

var url = "http://www.ebay.com/itm/Microsoft-Surface-Pro-3-12-"
          + "Tablet-256GB-SSD-Intel-Core-i7-Haswell-8GB-RAM-/281656969697";

$.getJSON("//query.yahooapis.com/v1/public/yql?" 
          + "q=SELECT%20*%20FROM%20html%20WHERE%20url=%27" 
          + encodeURIComponent(url) 
          + "%27%20AND%20xpath=%27descendant-or-self::meta%27"
          + "&format=json&callback=?"
  , function(data) {
      // `data`:`json` returned from request
      console.log(data);
      // filter returned `results.meta` array for
      // object having property `property`:`og:*` `meta` elements ;
      // and has `property` `og:image` 
      var res = $.grep(data.query.results.meta, function(image, key) {
        return image.hasOwnProperty("property") && image.property === "og:image"
      });
      // if object having property `og:image` returned , do stuff
      if (res.length > 0) {
        console.log(res[0].property);
        $("body").append(res[0].content);
      } else {
        // else, log notification
        console.log("og:image not found")
      };

});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js">
</script>

JSFiddle