title: JavaScript object check for key -- but ignore case
body: <p>Normally, I would do it like this</p>
  
  <pre><code>if (key in obj) {
      //other stuff
  }
  </code></pre>
  
  <p>But I don't actually know that they are capitalized the same. What's the best way to do this? I would rather not iterate through the whole array, calling <code>.toLowercase</code> on each key in the object, but is that the only option?</p>