Tryit Editor v1.8

Source Code:

<!DOCTYPE html>
<html>
<head>
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js">
</script>
<script>
$(document).ready(function(){
  $("button").click(function(){
      $("li").removeClass(function(n) {
      if (n==0||n==1) {return "listitem"}
      else {return ""}
    });
  });
});
</script>
<style type="text/css">
.listitem
{
color:red;
}
</style>
</head>
<body>

<h1>This is a heading</h1>
<ul>
<li class="listitem">Peter</li>
<li class="listitem">Lois</li>
<li class="listitem">Chris</li>
<li class="listitem">Stewie</li>
</ul>

<button>Remove class "listitem" from the li elements with index 0 and 1</button>

</body>
</html>

Result:

W3Schools.com - Try it yourself

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