title: Why gt() and lt() are only jQuery selectors, instead eq() is also a method?
body: <p>In jQuery, why only <code>eq()</code> is both a selector (:) and a method (.), instead <code>gt()</code> and <code>lt()</code> are only selectors ("Object doesn't support that property or method")?</p>
  
  <p>Is there a particular reason for this inconsistency/gap of jQuery syntax, that I do not understand?</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>$("#eq").click(function(){
    alert($("li").eq(0).text());
    $("li").eq(1).css("background-color", "yellow");
  });
  $("#eq2").click(function(){
    alert($("li:eq(0)").text());
    $("li:eq(1)").css("background-color", "yellow");
  });
  $("#gt").click(function(){
    $("li").gt(1).css("background-color", "yellow");
  });
  $("#gt2").click(function(){
    $("li:gt(1)").css("background-color", "yellow");
  });
  $("#lt").click(function(){
    $("li").lt(1).css("background-color", "yellow");
  });
  $("#lt2").click(function(){
    $("li:lt(1)").css("background-color", "yellow");
  });</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"&gt;&lt;/script&gt;
  &lt;ul id="indice"&gt;
   &lt;li&gt;Primo capitolo&lt;/li&gt;
   &lt;li&gt;Secondo capitolo
    &lt;ul&gt;
     &lt;li&gt;Sottocapitolo&lt;/li&gt;
    &lt;/ul&gt;
   &lt;/li&gt;
   &lt;li&gt;Terzo capitolo&lt;/li&gt;
  &lt;/ul&gt;
  &lt;button id="eq"&gt;.eq()&lt;/button&gt;
  &lt;button id="eq2"&gt;:eq()&lt;/button&gt;&lt;br&gt;
  &lt;button id="gt"&gt;.gt()&lt;/button&gt; &lt;!-- NO --&gt;
  &lt;button id="gt2"&gt;:gt()&lt;/button&gt;&lt;br&gt;
  &lt;button id="lt"&gt;.lt()&lt;/button&gt; &lt;!-- NO --&gt;
  &lt;button id="lt2"&gt;:lt()&lt;/button&gt;</code></pre>
  </div>
  </div>
  </p>