title: get value of an attribute after matching value of another attribute
body: <p>I'm completely new to jQuery/javascript and have been beating my head against this simple task for days.</p>
  
  <p>I want to find a meta element in a page with attribute <code>property="og:title"</code>, and then get the value of the attribute <code>"content"</code>, e.g.:</p>
  
  <p><code>&lt;meta property="og:title" content="Leaders Say Progress Made in Dealing With Euro Crisis"/&gt;</code></p>
  
  <p>so I want to get the text "Leaders Say Progress Made in Dealing With Euro Crisis", and perhaps write it within in the page or pass it to another function.</p>
  
  <p>How would I get the value of the content attribute? I tried <code>.$("meta [property='og:title']")</code> but then I realized that would try to get the non-existent text element.</p>