title: indexOf in Ruby
body: <p>Just wondering is there the same method for an Array object similar to indexOf in JavaScript?</p>
  
  <p>For example:</p>
  
  <pre>
  arr = %w{'a', 'b', 'c'}
  c = 'c'
  if (arr.indexOf(c) != -1)
  // do some stuff
  else
  // don't do some stuff
  </pre>