title: Should negative indexes in JavaScript arrays contribute to array length?
body: <p>In javascript I define an array like this</p>
  
  <pre><code>var arr = [1,2,3];
  </code></pre>
  
  <p>also I can do </p>
  
  <pre><code>arr[-1] = 4;
  </code></pre>
  
  <p>Now if I do</p>
  
  <pre><code>arr = undefined;
  </code></pre>
  
  <p>I also lose the reference to the value at <strong>arr[-1]</strong>.</p>
  
  <p>SO for me logically it seems like arr[-1] is also a part of <strong>arr</strong>.</p>
  
  <p>But when I do following (without setting arr to undefined)</p>
  
  <pre><code>arr.length;
  </code></pre>
  
  <p>It returns <strong>3</strong> not <strong>4</strong>;</p>
  
  <p>So my point is <strong>if the arrays can be used with negative indexes,</strong> these negative indexes should also be a part of their length**.
  I don't know may be I am wrong or I may be missing some concept about arrays.</p>