title: Regex to validate week and year
body: <p>I want to validate a string with this pattern: ww/yyyy.</p>
  
  <p>With: <code>^([0-9]{4})</code>, I check if the year has 4 digits.</p>
  
  <p>I tried to put these two regex together without success.</p>
  
  <pre><code>(5[0-3]|[1-4][0-9]|0[1-9])/^([0-9]{4})
  </code></pre>