title: regex to match first half of any string?
body: <p>I find this hard to do without variable quantifiers</p>
  
  <p>I'd like to be able to do something like</p>
  
  <pre><code>var halfStrLength = string.length /2 
  
  
  string = string.replace(/.(?=.{halfStrLength})/g, '*') 
  // replaces all but the last half of string with *
  </code></pre>