Try below method.

<a id="view_site_description" href="javascript:void(0);">View Our Site Description</a>

add_action( \'wp_footer\', \'add_js_to_wp_footer\' );
function add_js_to_wp_footer(){ ?>
    <script type="text/javascript">
    jQuery(\'#view_site_description\').click(function(){
        jQuery.ajax({
            type: \'POST\',
            url: ajaxurl,
            data: {"action": "myfilter"},
            success: function(data){alert(data);}
        });
        return false;
    });
    </script>
<?php }