jQuery removeClass()
remove class and add new class
<!DOCTYPE html> <html> <head> <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"> </script>/*www. ja va 2 s . co m*/ <script> $(document).ready(function(){ $("button").click(function(){ $("p:last").removeClass("intro").addClass("main"); }); }); </script> <style> .intro { color: red; } .main { background-color: yellow; } </style> </head> <body> <h1>This is a heading</h1> <p>This is another paragraph.</p> <p class="intro">This is a paragraph.</p> <button>Change class name of the last p element</button> </body> </html>