title: Custom data-attribute selector not working
body: <p>Any idea why this happens …</p>
  
  <pre><code>    var attr = $(this).data('link');
      console.log(attr); // profile_following
      console.log($("a[data-target='profile_following']")); // found the object
      console.log($("a[data-target='+attr+']")); // [] empty
  </code></pre>
  
  <p>Inside of a click handler I have the lines above!
  <code>console.log(attr);</code> successfully prints <code>profile_following</code>
  However if I try to select a link with an attribute selector and this variable like this <code>console.log($("a[data-target='+attr+']"));</code> it can't find the element! </p>
  
  <p>And the weirdest thing after all is if I hardcode the line like that <code>console.log($("a[data-target='profile_following']"));</code> it finds the object successfully. </p>
  
  <p>Any idea why the same line wouldn't work with the <code>+attr+</code> inside the attribute selector? </p>