title: JQuery Attr is not function
body: <p>I try to add attribute of option by using JQuery. I run this code.</p>
  
  <pre><code> $("option[value='430']").attr("selected","selected");
  </code></pre>
  
  <p>It return <strong>TypeError: $(...).attr is not a function(…)</strong></p>
  
  <p>I cannot saw my error. Where is the problem?</p>
  
  <p>Thanks.</p>