How to call ajax only once

I call function from this code :

    <div id="header-button-news" class="header-button-info">
        <a href="javascript:;" title="Новости" onclick="showNews()"></a>
        <div class="new">2</div>
    </div>

My function is

function showNews()
{          
        //other js which show block 

        jQuery("#loader").show();


        //ajax which load content to block
        jQuery.ajax({
            type: "GET",
            url: link,
            dataType: "html",
            success: function(data) {
                jQuery('#top-info-news').html(data);   
            },
            complete: function(){
                jQuery('#loader').hide();
            },
        });
}

How can I make only once ajax call? so when content is loaded and page was not refresed not to load ajax? I tried to do boolean variables but nothing, I suppouse it is because I call everytime function. Please give me an idea how to do.

thank you