title: Why aren't ◎ܫ◎ and ☺ valid JavaScript variable names?
body: <p>I noticed that in Internet Explorer (but, unfortunately, not in the other browsers I tested), you can use some Unicode variable names. This made my day, and I was absolutely delighted that I could write fun Unicode-laden code like this:</p>
  
  <pre><code>var ктоείναι草泥马 = "You dirty horse.",
      happy☺n☺mat☺p☺eia = ":)Yay!",
      ಠ_ಠ = "emoticon";
  
  alert(ктоείναι草泥马 + happy☺n☺mat☺p☺eia + ಠ_ಠ);
  </code></pre>
  
  <p>For some reason, though, <code>◎ܫ◎</code>, <code>♨_♨</code> and <code>☺</code> are not valid variable names.</p>
  
  <p>Why do <code>ಠ_ಠ</code> and <code>草泥马</code> work, but <code>◎ܫ◎</code>, <code>♨_♨</code> and <code>☺</code> don't?</p>
  
  <p>EDIT: Test it out in your browser on <a href="http://jsfiddle.net/h5Gsf/1/" rel="noreferrer">JSFiddle</a>. I've tested it in Internet&nbsp;Explorer&nbsp;9, Chrome, Firefox, and Opera. So far, it seems to only work in Internet&nbsp;Explorer&nbsp;9. (I don't know about Internet&nbsp;Explorer&nbsp;8 and below.) Let me know if it works in another browser.</p>