trouble updating multiple anchors aysc with jquery

So i have all these links in html like this

<a href="#ajax" class="invlink" competition_id="532">Gen Invoice</a>
<a href="#ajax" class="invlink" competition_id="534">Gen Invoice</a>
<a href="#ajax" class="invlink" competition_id="535">Gen Invoice</a>

then i wrote some javascript which binds to the click event and i want it to submit an ajax request, and replace the anchor with the returned text. but if i have clicked on multiple links so that several are running asychronously, then it doesn't update all the anchors with the returned text, only the last anchor i clicked on.

i am guessing that the anchor variable is being overwritten each time it is run, how would i structure my code so that each time the click event is triggered, it updates the correct anchor on completion?

here is the javascript

<script type="text/javascript">

    $(document).ready(function() {
        // bind geninvoice function to all invlink's
        $('.invlink').bind('click', geninvoice);
    });


    function geninvoice() {

        // stop double clicks
        anchor = $(this);
        anchor.unbind('click');

        competition_id = $(this).attr('competition_id');

        $.ajax({
            type: "POST",
            url: "<?php echo url::site('manage/ajax/geninvoice'); ?>/开发者_JAVA技巧"+competition_id,
            dataType: "json",
            beforeSend: function() {
                anchor.addClass("loading");
            },
            success: function(response, textStatus) {
                anchor.replaceWith(response.invoice_number);
            },
            error: function(response) {
                alert("Unknown Error Occurred");
                anchor.bind('click', geninvoice); // rebind if error occurs
            },
            complete: function() {
                anchor.removeClass("loading");
            }
        });
    }

</script>

---

Yeah, the problem is that your anchor variable as it is written being 'hoisted' to a global scope. See this jsfiddle for a simplified example.

You can fix this, by putting a var in front of the variable, so its scope will be limited to the function:

function geninvoice() {

    // stop double clicks
    var anchor = $(this); //<-- put a var here

You can see the fix at this updated version of the above fiddle

Note, this will only help you for scoping within functions. The x variable in the following example will be hoisted to the top of the global scope even though it has been declared with a var:

var a = 1;
var b = 1;

if (a === b){
   var x = 0;
}

alert(x); //alerts '0'

the advantages of scoping within functions is on of the reasons we often see the following convention around jQuery plugins:

(function($){
    //plugin code
    //all variables local to the invoked anonymous function
})(jQuery);

See at this JSFiddle