title: Javascript .toLowerCase/.toUpperCase in mixed mode
body: <p>I try to code some function. I want to change every 2nd letter <code>.toUpperCase</code>. I get it to work with <code>str.char[0].toUpperCase</code> but have to do it with the whole char numbers manually <code>(char[0],char[1],char[2])</code> and so on.</p>
  
  <p>Can someine help me out with an array which transforms a given string like this:
  <code>teststring</code> to: <code>tEsTsTrInG</code>. </p>
  
  <p>My problem is to built an array which takes every second letter of given string and changes it <code>.toUpperCase</code>.</p>