I want to delay a link for a period of 500 with javascript

Set your href attribute as href="javascript:delay('URL')" and JavaScript:

function delay (URL) {
    setTimeout( function() { window.location = URL }, 500 );
}

If you want to delay every link on your page, you can do it with jQuery like this

$(function(){
    $("a").click(function(evt){
        var link = $(this).attr("href");
        setTimeout(function() {
            window.location.href = link;
        }, 500);
    });
});