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(){
  $("p").mouseenter(function(){
    $("p").css("background-color","yellow");
  });
  $("p").mouseleave(function(){
    $("p").css("background-color","lightgray");
  });
  $("#btn1").click(function(){
    $("p").mouseenter();
  });  
  $("#btn2").click(function(){
    $("p").mouseleave();
  }); 
});
</script>
</head>
<body>

<p>This is a paragraph.</p>
<button id="btn1">Trigger mouseenter event</button><br>
<button id="btn2">Trigger mouseleave event</button>

</body>
</html>

Result:

W3Schools.com - Try it yourself

Edit the code above and click "Submit Code" to see the result.