onclick event pass

id or value

Try like this…

<script>
function getPaging(str) {
  $("#loading-content").load("dataSearch.php?"+str, hideLoader);
}
</script>

<li onclick="getPaging(this.id)" id="1">1</li>
<li onclick="getPaging(this.id)" id="2">2</li>

or unobtrusively

$(function() {
  $("li").on("click",function() {
    showLoader();
    $("#loading-content").load("dataSearch.php?"+this.id, hideLoader);
  });
});

using just

<li id="1">1</li>
<li id="2">2</li>