title: Pure function given strictly equal arguments yielding non-strictly equal results
body: <p>Below is a <a href="http://en.wikipedia.org/wiki/Pure_function" rel="noreferrer">pure function</a> <code>f</code> for which <code>f(a) !== f(b)</code> despite <code>a === b</code> (notice the <em>strict</em> equalities) for some values of <code>a</code> and <code>b</code>:</p>
  
  <pre><code>var f = function (x) {
     return 1 / x;
  }
  
  +0 === -0 // true
  f(+0) === f(-0) // false
  </code></pre>
  
  <p>The existence of such functions can lead to difficult-to-find bugs. Are there other examples I should be weary of?</p>