title: Remove elements having length less than `n`, in a LARGE sorted array
body: <p>At first let me explain what I want. Well, I have a sorted array like this</p>
  
  <pre><code>var arr = ["ab", "abcd", "abdf", "abcdd", "abcdd", "abcdfd", "abcdsss", "abcdefgh", "abcdsdsdsds"];
  </code></pre>
  
  <p>Now I need to remove all elements which string length is less than 5. Ok, Now my point is, is there any easiest way to find the index of the element that string length is 4. Likes here two elements contain string length 4. But I need the last one. If it is possible to get that index I can apply</p>
  
  <pre><code>arr.splice(0, (index+1));
  </code></pre>
  
  <p>And one thing, my original array contain 1 million data. Now how can I solve  this?</p>