Apply CSS onclick

better to just use .addClass even if you have 1 or more. It's more maintainable and readable.

If you really have the urge to do multiple css props then use

$("a:nth-child(4)").click(function () {
    $(".artists").animate({width:'toggle'},500);
    $('body').css({
                 '-webkit-filter': 'blur(20px)', 
                 '-moz-filter': 'blur(15px)', 
                 '-o-filter: blur(15px)', 
                 '-ms-filter': 'blur(15px)', 
                 'filter': 'blur(15px)', 
                 'opacity': '0.95'
                 });               
});

If you want to do it without jQuery:

<script>
    window.onload = function() {
        var anchors = document.getElementsByTagName('a');
        for(var i = 0; i < anchors.length; i++) {
            var anchor = anchors[i];
            anchor.onclick = function() {
                alert('ho ho ho');
            }
        }
    }
</script>

And to do it without jQuery, and only on a specific class (ex: hohoho):

<script>
    window.onload = function() {
        var anchors = document.getElementsByTagName('a');
        for(var i = 0; i < anchors.length; i++) {
            var anchor = anchors[i];
            if(/\bhohoho\b/).match(anchor.className)) {
                anchor.onclick = function() {
                    alert('ho ho ho');
                }
            }
        }
    }
</script>
If you are okay with using jQuery, then you can do this for all anchors:

<script>
    $(document).ready(function() {
        $('a').click(function() {
            alert('ho ho ho');
        });
    });
</script>

And this jQuery snippet to only apply it to anchors with a specific class:

<script>
    $(document).ready(function() {
        $('a.hohoho').click(function() {
            alert('ho ho ho');
        });
    });
</script>