title: Select elements by attribute
body: <p>I have a collection of checkboxes with generated ids and some of them have an extra attribute. Is it possible to use JQuery to check if an element has a specific attribute?
  For example, can I verify if the following element has the attribute "myattr"? The value of the attribute can vary.</p>
  
  <pre><code>&lt;input type="checkbox" id="A" myattr="val_attr"&gt;A&lt;/input&gt;
  </code></pre>
  
  <p>For example how can I get a collection of all checkboxes that have this attribute without checking one by one? Is this possible?</p>