title: Match substring that start with prefix
body: <p>I am stuck with a little regular expression
  I am trying to match every substring that start with a given prefix using regular expression
  in javascript</p>
  
  <pre><code>prefix = "pre-"
  regex = /???/
  
  "pre-foo-bar bar pre-bar barfoo".replace(regex, '')
  // should output "bar barfoo"
  </code></pre>