Edit in JSFiddle

$(document).ready(function() {
  $("button").click(function() {
    var firstObj = $("#content p").first(); 
    console.log(firstObj[0]); // gets the first p element
    var lastObj = $("#content p").eq(1);
    console.log(lastObj[0]); // gets the p element at index 1
    filteredObj = $("#content p").filter(".demo");
    console.log(filteredObj[0]); // gets the p element with class demo
  });
});

<h2>jCombat Demo - jQuery DOM Manipulations</h2>

<div id="content">
  <p>This is a paragraph. <a href="#">Sample Link</a></p>
  <p class="demo">This is another paragraph.</p>
</div>

<button>Click here</button>