title: How to check if a key exists in a complex object in Javascript?
body: <pre><code>title = title.replace(':AppName', App.name)
  title = title.replace(':AppLogo', App.logo)
  title = title.replace(':boardName', page.data.board.name)
  title = title.replace(':articleTitle', page.data.article.title)
  title = title.replace(':articleAuthor', page.data.article.author)
  title = ...
  </code></pre>
  
  <p>I have to replace the long title several times. Depending on the page, because the structure of the title changes, the key of the object may be repeated or not exist.</p>
  
  <p>Do you have any good ideas besides using 'try catch'?</p>