title: What is the correct readonly attribute syntax for input text elements?
body: <p>As Most, I am familiar with the <code>readonly</code> attribute for <code>text input</code>, But while reading code from other websites (a nasty habit of mine ) I saw more than one implementation for this attribute:</p>
  
  <pre><code>&lt;input type="text" value="myvalue" class="class anotherclass" readonly &gt;
  </code></pre>
  
  <p>and </p>
  
  <pre><code>&lt;input type="text" value="myvalue" class="class anotherclass" readonly="readonly" &gt;
  </code></pre>
  
  <p>and I have even seen </p>
  
  <pre><code>&lt;input type="text" value="myvalue" class="class anotherclass" readonly="true" &gt;
  </code></pre>
  
  <p>.. And I believe I saw even more, but can not recall the exact syntax now..</p>
  
  <p>So, which one is the correct one that I should use?</p>