javascript - How I know the url when wants to make a json request?

Question

Hej,

Seems a bit stupid to ask but really want to know. For example, I want to get the information under the title "Identification" in the following webpage,"http://en.wikipedia.org/wiki/Tag#Identification" then I could use script :

<script type="text/javascript">
$(document).ready(function() {
    var url =  "";
    $.getJSON(url + "?callback=?", null, function(wiki) {
      <!-- code -->
});
</script>

but in this case, what's the url should be?