<link href="//netdna.bootstrapcdn.com/bootstrap/3.0.0/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css"> <script src="//netdna.bootstrapcdn.com/bootstrap/3.0.0/js/bootstrap.min.js"></script> <script src="//code.jquery.com/jquery-1.11.1.min.js"></script> <!------ Include the above in your HEAD tag ----------> <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css"> <div class="container"> <div class="row"> <hr> <div class="col-md-4 col-md-offset-4" align="center"> <i id="item" class="fa fa-square-o fa-5x" onclick="change(this.id)"></i> </div> </div> </div>

function change(id){ document.getElementById(id).setAttribute("class", "fa fa-check-square-o fa-5x"); }