Tryit Editor v1.7

Source Code:

Result:

<!DOCTYPE html>
<html>
<head>
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js">
</script>
<script>
$(document).ready(function(){
  $("p:only-of-type").css("background-color","yellow");
});
</script>
</head>
<body>

<div style="border:1px solid;">
<p>The first paragraph.</p>
<p>The last paragraph.</p>
</div><br>

<div style="border:1px solid;">
<p>The only paragraph.</p>
</div><br>

<div style="border:1px solid;">
<span>This is a span element.</span>
<p>The only paragraph.</p>
</div><br>

</body>
</html>

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

W3Schools.com - Try it yourself

Source Code:	Result:
<!DOCTYPE html> <html> <head> <script src="//ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"> </script> <script> $(document).ready(function(){ $("p:only-of-type").css("background-color","yellow"); }); </script> </head> <body> <div style="border:1px solid;"> <p>The first paragraph.</p> <p>The last paragraph.</p> </div><br> <div style="border:1px solid;"> <p>The only paragraph.</p> </div><br> <div style="border:1px solid;"> <span>This is a span element.</span> <p>The only paragraph.</p> </div><br> </body> </html>
Edit the code above and click "Submit Code" to see the result.	W3Schools.com - Try it yourself