title: Check if TextArea/TextBox contains a certain String
body: <p>Given textarea is a textarea element with id 'textareabox', how can I check if it contains a string within it?</p>
  
  <pre><code>var textarea = document.getElementById('textareabox');
  
  var word = something;
  
  if (!textarea.contains(word))
  {
  textarea.value += word;
  }
  </code></pre>