[jQuery] [BlockUI Plugin]use links instead of buttons

[jQuery] [BlockUI Plugin]use links instead of buttons


At script's demo page, blockui's developer used buttons to activate
the scripts. How can I use links instead?
I tried it as below but it did not work.
<a href="javascript:void(0)" id="demo5">xxx</a>
html:
        <button id="demo5">Run</button>
js:
    $(document).ready(function() {
        $('#demo5').click(function() {
            $.blockUI({
                message: $('img#productimage'),
                css: {
                    top: ($(window).height() - 500) /2 + 'px',
                    left: ($(window).width() - 500) /2 + 'px',
                    width: '500px'
                }
            });
            setTimeout($.unblockUI, 2000);
        });
    });