Edit in JSFiddle

Result
JavaScript
HTML
CSS

 $(document).ready(function () {
                var className = "default changed";
                $("#checkP").click(function () {
                    var hasClass = $("p").hasClass(className);
                    alert("p has class " + className + " ?? : " + hasClass);
                });
                $("#checkSpan").click(function () {
                    var hasClass = $("span").hasClass(className);
                    alert("span has class  " + className + " ?? : " + hasClass);
                });
            });

<html>
        <head>
        <title>hasClass</title>
        </head>
        <body>
        <p class="default changed">This is paragraph element.</p>
        <span>This is span element.</span><br /><br />
        <input type="button" id="checkP" value="Check p for default class" />
        <input type="button" id="checkSpan" value="Check span for default class" />
        </body>
        </html>

.default
        {
        color:Red;
        }
        .changed
        {
        font-family:comic sans ms;
        }